Leukemia
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Leukemia ( also spelled leukaemia and pronounced ) is a group of
blood cancer Tumors of the hematopoietic and lymphoid tissues (American English) or tumours of the haematopoietic and lymphoid tissues (British English) are tumors that affect the blood, bone marrow, lymph, and lymphatic system. Because these tissues are all ...
s that usually begin in the bone marrow and result in high numbers of abnormal
blood cell A blood cell, also called a hematopoietic cell, hemocyte, or hematocyte, is a cell produced through hematopoiesis and found mainly in the blood. Major types of blood cells include red blood cells (erythrocytes), white blood cells (leukocytes) ...
s. These blood cells are not fully developed and are called ''blasts'' or ''leukemia cells''. Symptoms may include bleeding and
bruising A bruise, also known as a contusion, is a type of hematoma of tissue, the most common cause being capillaries damaged by trauma, causing localized bleeding that extravasates into the surrounding interstitial tissues. Most bruises occur clos ...
,
bone pain Bone pain (also known medically by several other names) is pain coming from a bone, and is caused by damaging stimuli. It occurs as a result of a wide range of diseases or physical conditions or both, and may severely impair the quality of life. ...
, fatigue,
fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...
, and an increased risk of infections. These symptoms occur due to a lack of normal
blood cell A blood cell, also called a hematopoietic cell, hemocyte, or hematocyte, is a cell produced through hematopoiesis and found mainly in the blood. Major types of blood cells include red blood cells (erythrocytes), white blood cells (leukocytes) ...
s. Diagnosis is typically made by blood tests or
bone marrow biopsy Bone marrow examination refers to the pathologic analysis of samples of bone marrow obtained by bone marrow biopsy (often called trephine biopsy) and bone marrow aspiration. Bone marrow examination is used in the diagnosis of a number of conditio ...
. The exact cause of leukemia is unknown. A combination of genetic factors and environmental (non-inherited) factors are believed to play a role. Risk factors include smoking, ionizing radiation, petrochemicals (such as
benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...
), prior chemotherapy, and
Down syndrome Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual dis ...
. People with a family history of leukemia are also at higher risk. There are four main types of leukemia— acute lymphoblastic leukemia (ALL),
acute myeloid leukemia Acute myeloid leukemia (AML) is a cancer of the myeloid line of blood cells, characterized by the rapid growth of abnormal cells that build up in the bone marrow and blood and interfere with normal blood cell production. Symptoms may inclu ...
(AML), chronic lymphocytic leukemia (CLL) and
chronic myeloid leukemia Chronic myelogenous leukemia (CML), also known as chronic myeloid leukemia, is a cancer of the white blood cells. It is a form of leukemia characterized by the increased and unregulated growth of myeloid cells in the bone marrow and the accumulati ...
(CML)—as well as a number of less common types. Leukemias and
lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enla ...
s both belong to a broader group of
tumor A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
s that affect the blood, bone marrow, and lymphoid system, known as
tumors of the hematopoietic and lymphoid tissues Tumors of the hematopoietic and lymphoid tissues (American English) or tumours of the haematopoietic and lymphoid tissues (British English) are tumors that affect the blood, bone marrow, lymph, and lymphatic system. Because these tissues are al ...
. Treatment may involve some combination of
chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemothe ...
,
radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radi ...
,
targeted therapy Targeted therapy or molecularly targeted therapy is one of the major modalities of medical treatment ( pharmacotherapy) for cancer, others being hormonal therapy and cytotoxic chemotherapy. As a form of molecular medicine, targeted therapy blocks ...
, and
bone marrow transplant Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood in order to replicate inside of a patient and to produce ...
, in addition to supportive care and
palliative care Palliative care (derived from the Latin root , or 'to cloak') is an interdisciplinary medical caregiving approach aimed at optimizing quality of life and mitigating suffering among people with serious, complex, and often terminal illnesses. Wit ...
as needed. Certain types of leukemia may be managed with
watchful waiting Watchful waiting (also watch and wait or WAW) is an approach to a medical problem in which time is allowed to pass before medical intervention or therapy is used. During this time, repeated testing may be performed. Related terms include ''expe ...
. The success of treatment depends on the type of leukemia and the age of the person. Outcomes have improved in the developed world.
Five-year survival rate The five-year survival rate is a type of survival rate for estimating the prognosis of a particular disease, normally calculated from the point of diagnosis. Lead time bias from earlier diagnosis can affect interpretation of the five-year surviva ...
is 65% in the United States. In children under 15 in first-world countries, the five-year survival rate is greater than 60% or even 90%, depending on the type of leukemia. In children with acute leukemia who are cancer-free after five years, the cancer is unlikely to return. In 2015, leukemia was present in 2.3 million people worldwide and caused 353,500 deaths. In 2012 it newly developed in 352,000 people. It is the most common type of cancer in children, with three-quarters of leukemia cases in children being the acute lymphoblastic type. However, over 90% of all leukemias are diagnosed in adults, with CLL and AML being most common in adults. It occurs more commonly in the
developed world A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...
. The term "leukemia" was coined in 1851 by R. Virchow from Greek ''leukos'' ("clear, white") and ''haima'' ("blood"). It was formerly also called "leucemia".


Classification


General classification

Clinically and pathologically, leukemia is subdivided into a variety of large groups. The first division is between its ''
acute Acute may refer to: Science and technology * Acute angle ** Acute triangle ** Acute, a leaf shape in the glossary of leaf morphology * Acute (medicine), a disease that it is of short duration and of recent onset. ** Acute toxicity, the adverse eff ...
'' and '' chronic'' forms: *
Acute leukemia Acute leukemia or acute leukaemia is a family of serious medical conditions relating to an original diagnosis of leukemia. In most cases, these can be classified according to the lineage, myeloid or lymphoid, of the malignant cells that grow unco ...
is characterized by a rapid increase in the number of immature blood cells. The crowding that results from such cells makes the bone marrow unable to produce healthy blood cells resulting in low
hemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyt ...
and low platelets. Immediate treatment is required in acute leukemia because of the rapid progression and accumulation of the malignant cells, which then spill over into the bloodstream and spread to other organs of the body. Acute forms of leukemia are the most common forms of leukemia in children. * Chronic leukemia is characterized by the excessive buildup of relatively mature, but still abnormal,
white blood cells White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from mult ...
. Typically taking months or years to progress, the cells are produced at a much higher rate than normal, resulting in many abnormal white blood cells. Whereas acute leukemia must be treated immediately, chronic forms are sometimes monitored for some time before treatment to ensure maximum effectiveness of therapy. Chronic leukemia mostly occurs in older people but can occur in any age group. Additionally, the diseases are subdivided according to which kind of blood cell is affected. This divides leukemias into lymphoblastic or ''
lymphocytic leukemia Lymphoid leukemias are a group of leukemias affecting circulating lymphocytes, a type of white blood cell. The lymphocytic leukemias are closely related to lymphomas of the lymphocytes, to the point that some of them are unitary disease entities t ...
s'' and myeloid or '' myelogenous leukemias'': * In lymphoblastic or
lymphocytic leukemia Lymphoid leukemias are a group of leukemias affecting circulating lymphocytes, a type of white blood cell. The lymphocytic leukemias are closely related to lymphomas of the lymphocytes, to the point that some of them are unitary disease entities t ...
s, the cancerous change takes place in a type of marrow cell that normally goes on to form
lymphocyte A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic ad ...
s, which are infection-fighting immune system cells. Most lymphocytic leukemias involve a specific subtype of lymphocyte, the B cell. * In myeloid or myelogenous leukemias, the cancerous change takes place in a type of marrow cell that normally goes on to form
red blood cell Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...
s, some other types of white cells, and
platelet Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby i ...
s. Combining these two classifications provides a total of four main categories. Within each of these main categories, there are typically several subcategories. Finally, some rarer types are usually considered to be outside of this classification scheme.


Specific types

* Acute lymphoblastic leukemia (ALL) is the most common type of leukemia in young children. It also affects adults, especially those 65 and older. Standard treatments involve
chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemothe ...
and radiotherapy. Subtypes include precursor B acute lymphoblastic leukemia, precursor T acute lymphoblastic leukemia, Burkitt's leukemia, and acute biphenotypic leukemia. While most cases of ALL occur in children, 80% of deaths from ALL occur in adults. * Chronic lymphocytic leukemia (CLL) most often affects adults over the age of 55. It sometimes occurs in younger adults, but it almost never affects children. Two-thirds of affected people are men. The five-year survival rate is 85%. It is incurable, but there are many effective treatments. One subtype is
B-cell prolymphocytic leukemia B-cell prolymphocytic leukemia, referred to as B-PLL, is a rare blood cancer. It is a more aggressive, but still treatable, form of leukemia. Specifically, B-PLL is a prolymphocytic leukemia (PLL) that affects prolymphocytes – immature forms o ...
, a more aggressive disease. *
Acute myelogenous leukemia Acute myeloid leukemia (AML) is a cancer of the myeloid line of blood cells, characterized by the rapid growth of abnormal cells that build up in the bone marrow and blood and interfere with normal blood cell production. Symptoms may includ ...
(AML) occurs far more commonly in adults than in children, and more commonly in men than women. It is treated with chemotherapy. The five-year survival rate is 20%. Subtypes of AML include acute promyelocytic leukemia,
acute myeloblastic leukemia Acute myeloid leukemia (AML) is a cancer of the myeloid line of blood cells, characterized by the rapid growth of abnormal cells that build up in the bone marrow and blood and interfere with normal blood cell production. Symptoms may include ...
, and
acute megakaryoblastic leukemia Acute megakaryoblastic leukemia (AMKL) is life-threatening leukemia in which malignant megakaryoblasts proliferate abnormally and injure various tissues. Megakaryoblasts are the most immature precursor cells in a platelet-forming lineage; they matu ...
. * Chronic myelogenous leukemia (CML) occurs mainly in adults; a very small number of children also develop this disease. It is treated with imatinib (Gleevec in United States, Glivec in Europe) or other drugs. The five-year survival rate is 90%. One subtype is
chronic myelomonocytic leukemia Chronic myelomonocytic leukemia (CMML) is a type of leukemia, which are cancers of the blood-forming cells of the bone marrow. In adults, blood cells are formed in the bone marrow, by a process that is known as haematopoiesis. In CMML, there are i ...
. *
Hairy cell leukemia Hairy cell leukemia is an uncommon hematological malignancy characterized by an accumulation of abnormal B lymphocytes. It is usually classified as a subtype of chronic lymphocytic leukemia (CLL). Hairy cell leukemia makes up about 2% of all leu ...
(HCL) is sometimes considered a subset of chronic lymphocytic leukemia, but does not fit neatly into this category. About 80% of affected people are adult men. No cases in children have been reported. HCL is incurable but easily treatable. Survival is 96% to 100% at ten years. *
T-cell prolymphocytic leukemia T-cell-prolymphocytic leukemia (T-PLL) is a mature T-cell leukemia with aggressive behavior and predilection for blood, bone marrow, lymph nodes, liver, spleen, and skin involvement. T-PLL is a very rare leukemia, primarily affecting adults over t ...
(T-PLL) is a very rare and aggressive leukemia affecting adults; somewhat more men than women are diagnosed with this disease. Despite its overall rarity, it is the most common type of mature
T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...
leukemia; nearly all other leukemias involve
B cells B cells, also known as B lymphocytes, are a type of white blood cell of the lymphocyte subtype. They function in the humoral immunity component of the adaptive immune system. B cells produce antibody molecules which may be either secreted o ...
. It is difficult to treat, and the median survival is measured in months. *
Large granular lymphocytic leukemia Large granular lymphocytic (LGL) leukemia is a chronic lymphoproliferative disorder that exhibits an unexplained, chronic (> 6 months) elevation in large granular lymphocytes (LGLs) in the peripheral blood. It is divided in two main categories: T- ...
may involve either T-cells or
NK cell Natural killer cells, also known as NK cells or large granular lymphocytes (LGL), are a type of cytotoxic lymphocyte critical to the innate immune system that belong to the rapidly expanding family of known innate lymphoid cells (ILC) and represen ...
s; like hairy cell leukemia, which involves solely B cells, it is a rare and indolent (not aggressive) leukemia. * Adult T-cell leukemia is caused by
human T-lymphotropic virus The human T-lymphotropic virus, human T-cell lymphotropic virus, or human T-cell leukemia-lymphoma virus (HTLV) family of viruses are a group of human retroviruses that are known to cause a type of cancer called adult T-cell leukemia/lymphoma an ...
(HTLV), a virus similar to
HIV The human immunodeficiency viruses (HIV) are two species of ''Lentivirus'' (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune ...
. Like HIV, HTLV infects CD4+ T-cells and replicates within them; however, unlike HIV, it does not destroy them. Instead, HTLV "immortalizes" the infected T-cells, giving them the ability to proliferate abnormally. Human T-cell lymphotropic virus types I and II (HTLV-I/II) are endemic in certain areas of the world. *
Clonal eosinophilia Clonal hypereosinophilia, also termed primary hypereosinophilia or clonal eosinophilia, is a grouping of hematological disorders all of which are characterized by the development and growth of a pre-malignant or malignant population of eosinophils ...
s (also called ''clonal hypereosinophilias'') are a group of blood disorders characterized by the growth of
eosinophil Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. A ...
s in the bone marrow, blood, and/or other tissues. They may be pre-cancerous or
cancerous Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bl ...
. Clonal eosinophilias involve a "clone" of eosinophils, i.e., a group of genetically identical eosinophils that all grew from the same mutated ancestor cell. These disorders may evolve into
chronic eosinophilic leukemia Chronic eosinophilic leukemia is a form of cancer in which too many eosinophils are found in the bone marrow, blood, and other tissues. Most cases are associated with fusion genes. Signs and symptoms Signs and symptoms may include weight loss, f ...
or may be associated with various forms of myeloid neoplasms,
lymphoid The lymphatic system, or lymphoid system, is an organ system in vertebrates that is part of the immune system, and complementary to the circulatory system. It consists of a large network of lymphatic vessels, lymph nodes, lymphatic or lymphoid o ...
neoplasms,
myelofibrosis Primary myelofibrosis (PMF) is a rare bone marrow blood cancer. It is classified by the World Health Organization (WHO) as a type of myeloproliferative neoplasm, a group of cancers in which there is growth of abnormal cells in the bone marrow. ...
, or the
myelodysplastic syndrome A myelodysplastic syndrome (MDS) is one of a group of cancers in which immature blood cells in the bone marrow do not mature, and as a result, do not develop into healthy blood cells. Early on, no symptoms typically are seen. Later, symptoms may ...
.


Pre-leukemia

*
Transient myeloproliferative disease Transient myeloproliferative disease (TMD) occurs in a significant percentage of individuals born with the congenital genetic disorder, Down syndrome. It may occur in individuals who are not diagnosed with the syndrome but have some hematological c ...
, also termed transient leukemia, involves the abnormal proliferation of a clone of non-cancerous megakaryoblasts. The disease is restricted to individuals with
Down syndrome Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual dis ...
or genetic changes similar to those in Down syndrome, develops in a baby during pregnancy or shortly after birth, and resolves within 3 months or, in ~10% of cases, progresses to
acute megakaryoblastic leukemia Acute megakaryoblastic leukemia (AMKL) is life-threatening leukemia in which malignant megakaryoblasts proliferate abnormally and injure various tissues. Megakaryoblasts are the most immature precursor cells in a platelet-forming lineage; they matu ...
. Transient myeloid leukemia is a pre-leukemic condition.


Signs and symptoms

The most common symptoms in children are easy
bruising A bruise, also known as a contusion, is a type of hematoma of tissue, the most common cause being capillaries damaged by trauma, causing localized bleeding that extravasates into the surrounding interstitial tissues. Most bruises occur clos ...
,
pale skin Pallor is a pale color of the skin that can be caused by illness, emotional shock or stress, stimulant use, or anemia, and is the result of a reduced amount of oxyhaemoglobin and may also be visible as pallor of the conjunctivae of the eyes o ...
,
fever Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...
, and an enlarged spleen or
liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...
. Damage to the bone marrow, by way of displacing the normal bone marrow cells with higher numbers of immature white blood cells, results in a lack of blood
platelet Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby i ...
s, which are important in the
blood clotting Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanis ...
process. This means people with leukemia may easily become bruised, bleed excessively, or develop pinprick bleeds ( petechiae). White blood cells, which are involved in fighting
pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...
s, may be suppressed or dysfunctional. This could cause the person's immune system to be unable to fight off a simple infection or to start attacking other body cells. Because leukemia prevents the immune system from working normally, some people experience frequent
infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dis ...
, ranging from infected
tonsil The tonsils are a set of lymphoid organs facing into the aerodigestive tract, which is known as Waldeyer's tonsillar ring and consists of the adenoid tonsil, two tubal tonsils, two palatine tonsils, and the lingual tonsils. These organs play ...
s, sores in the mouth, or
diarrhea Diarrhea, also spelled diarrhoea, is the condition of having at least three loose, liquid, or watery bowel movements each day. It often lasts for a few days and can result in dehydration due to fluid loss. Signs of dehydration often begin w ...
to life-threatening
pneumonia Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severi ...
or opportunistic infections. Finally, the red blood cell deficiency leads to
anemia Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, t ...
, which may cause
dyspnea Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing di ...
and pallor. Some people experience other symptoms, such as fevers, chills, night sweats, weakness in the limbs, feeling fatigued and other common
flu-like symptoms Influenza-like illness (ILI), also known as flu-like syndrome or flu-like symptoms, is a medical diagnosis of possible influenza or other illness causing a set of common symptoms. These include fever, shivering, chills, malaise, dry cough, loss ...
. Some people experience nausea or a feeling of fullness due to an enlarged
liver The liver is a major organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the synthesis of proteins and biochemicals necessary for digestion and growth. In humans, it ...
and
spleen The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .
; this can result in unintentional
weight loss Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat ( adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other co ...
. Blasts affected by the disease may come together and become swollen in the liver or in the
lymph nodes A lymph node, or lymph gland, is a kidney-shaped organ of the lymphatic system and the adaptive immune system. A large number of lymph nodes are linked throughout the body by the lymphatic vessels. They are major sites of lymphocytes that inclu ...
causing pain and leading to nausea. If the leukemic cells invade the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
, then neurological symptoms (notably headaches) can occur. Uncommon neurological symptoms like migraines,
seizures An epileptic seizure, informally known as a seizure, is a period of symptoms due to abnormally excessive or synchronous neuronal activity in the brain. Outward effects vary from uncontrolled shaking movements involving much of the body with l ...
, or coma can occur as a result of brain stem pressure. All symptoms associated with leukemia can be attributed to other diseases. Consequently, leukemia is always diagnosed through
medical test A medical test is a medical procedure performed to detect, diagnose, or monitor diseases, disease processes, susceptibility, or to determine a course of treatment. Medical tests such as, physical and visual exams, diagnostic imaging, genetic ...
s. The word ''leukemia'', which means 'white blood', is derived from the characteristic high white blood cell count that presents in most affected people before treatment. The high number of white blood cells is apparent when a blood sample is viewed under a microscope, with the extra white blood cells frequently being immature or dysfunctional. The excessive number of cells can also interfere with the level of other cells, causing further harmful imbalance in the blood count. Some people diagnosed with leukemia do not have high white blood cell counts visible during a regular blood count. This less-common condition is called ''aleukemia''. The bone marrow still contains cancerous white blood cells that disrupt the normal production of blood cells, but they remain in the marrow instead of entering the bloodstream, where they would be visible in a blood test. For a person with aleukemia, the white blood cell counts in the bloodstream can be normal or low. Aleukemia can occur in any of the four major types of leukemia, and is particularly common in
hairy cell leukemia Hairy cell leukemia is an uncommon hematological malignancy characterized by an accumulation of abnormal B lymphocytes. It is usually classified as a subtype of chronic lymphocytic leukemia (CLL). Hairy cell leukemia makes up about 2% of all leu ...
.


Causes

There is no single known cause for any of the different types of leukemias. The few known causes, which are not generally factors within the control of the average person, account for relatively few cases. The cause for most cases of leukemia is unknown. The different leukemias likely have different causes. Leukemia, like other cancers, results from mutations in the DNA. Certain mutations can trigger leukemia by activating
oncogene An oncogene is a gene that has the potential to cause cancer. In tumor cells, these genes are often mutated, or expressed at high levels.
s or deactivating
tumor suppressor gene A tumor suppressor gene (TSG), or anti-oncogene, is a gene that regulates a cell during cell division and replication. If the cell grows uncontrollably, it will result in cancer. When a tumor suppressor gene is mutated, it results in a loss or re ...
s, and thereby disrupting the regulation of cell death, differentiation or division. These mutations may occur spontaneously or as a result of exposure to radiation or
carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...
ic substances. Among adults, the known causes are natural and artificial ionizing radiation and petrochemicals, notably
benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...
and alkylating
chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemothe ...
agents for previous malignancies. Use of
tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...
is associated with a small increase in the risk of developing
acute myeloid leukemia Acute myeloid leukemia (AML) is a cancer of the myeloid line of blood cells, characterized by the rapid growth of abnormal cells that build up in the bone marrow and blood and interfere with normal blood cell production. Symptoms may inclu ...
in adults. Cohort and case-control studies have linked exposure to some petrochemicals and hair dyes to the development of some forms of leukemia. Diet has very limited or no effect, although eating more vegetables may confer a small protective benefit. Viruses have also been linked to some forms of leukemia. For example,
human T-lymphotropic virus The human T-lymphotropic virus, human T-cell lymphotropic virus, or human T-cell leukemia-lymphoma virus (HTLV) family of viruses are a group of human retroviruses that are known to cause a type of cancer called adult T-cell leukemia/lymphoma an ...
(HTLV-1) causes adult T-cell leukemia. A few cases of maternal-fetal transmission (a baby acquires leukemia because its mother had leukemia during the pregnancy) have been reported. Children born to mothers who use fertility drugs to induce ovulation are more than twice as likely to develop leukemia during their childhoods than other children. In a recent systematic review and meta-analysis, a statistically significant association was detected between neonatal phototherapy and any type of leukemia, and myeloid leukemia. However, it is still questionable whether phototherapy is genuinely the cause of cancer or simply a result of the same underlying factors that gave rise to cancer.


Radiation

Large doses of Sr-90 emission from
nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat fr ...
accidents, nicknamed bone seeker increases the risk of
bone cancer A bone tumor is an abnormal growth of tissue in bone, traditionally classified as noncancerous (benign) or cancerous (malignant). Cancerous bone tumors usually originate from a cancer in another part of the body such as from lung, breast, thy ...
and leukemia in animals and is presumed to do so in people.


Genetic conditions

Some people have a genetic predisposition towards developing leukemia. This predisposition is demonstrated by family histories and
twin studies Twin studies are studies conducted on identical or fraternal twins. They aim to reveal the importance of environmental and genetic influences for traits, phenotypes, and disorders. Twin research is considered a key tool in behavioral genetics ...
. The affected people may have a single gene or multiple genes in common. In some cases, families tend to develop the same kinds of leukemia as other members; in other families, affected people may develop different forms of leukemia or related blood cancers. In addition to these genetic issues, people with chromosomal abnormalities or certain other genetic conditions have a greater risk of leukemia. For example, people with
Down syndrome Down syndrome or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21. It is usually associated with physical growth delays, mild to moderate intellectual dis ...
have a significantly increased risk of developing forms of acute leukemia (especially
acute myeloid leukemia Acute myeloid leukemia (AML) is a cancer of the myeloid line of blood cells, characterized by the rapid growth of abnormal cells that build up in the bone marrow and blood and interfere with normal blood cell production. Symptoms may inclu ...
), and
Fanconi anemia Fanconi anaemia (FA) is a rare genetic disease resulting in impaired response to DNA damage. Although it is a very rare disorder, study of this and other bone marrow failure syndromes has improved scientific understanding of the mechanisms of no ...
is a risk factor for developing acute myeloid leukemia. Mutation in SPRED1 gene has been associated with a predisposition to childhood leukemia. Chronic myelogenous leukemia is associated with a genetic abnormality called the Philadelphia translocation; 95% of people with CML carry the Philadelphia mutation, although this is not exclusive to CML and can be observed in people with other types of leukemia.


Non-ionizing radiation

Whether or not non-ionizing radiation causes leukemia has been studied for several decades. The
International Agency for Research on Cancer The International Agency for Research on Cancer (IARC; french: Centre International de Recherche sur le Cancer, CIRC) is an intergovernmental agency forming part of the World Health Organization of the United Nations. Its role is to conduct and ...
expert working group undertook a detailed review of all data on static and
extremely low frequency Extremely low frequency (ELF) is the ITU designation for electromagnetic radiation (radio waves) with frequencies from 3 to 30  Hz, and corresponding wavelengths of 100,000 to 10,000 kilometers, respectively. In atmospheric scien ...
electromagnetic energy, which occurs naturally and in association with the generation, transmission, and use of electrical power. They concluded that there is limited evidence that high levels of
ELF An elf () is a type of humanoid supernatural being in Germanic mythology and folklore. Elves appear especially in North Germanic mythology. They are subsequently mentioned in Snorri Sturluson's Icelandic Prose Edda. He distinguishes "ligh ...
magnetic (but not electric) fields might cause some cases of childhood leukemia. No evidence for a relationship to leukemia or another form of malignancy in adults has been demonstrated. Since exposure to such levels of ELFs is relatively uncommon, the
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of ...
concludes that ELF exposure, if later proven to be causative, would account for just 100 to 2400 cases worldwide each year, representing 0.2 to 4.9% of the total incidence of childhood leukemia for that year (about 0.03 to 0.9% of all leukemias).


Diagnosis

Diagnosis is usually based on repeated
complete blood count A complete blood count (CBC), also known as a full blood count (FBC), is a set of medical laboratory tests that provide information about the cells in a person's blood. The CBC indicates the counts of white blood cells, red blood cells and pl ...
s and a
bone marrow examination Bone marrow examination refers to the pathologic analysis of samples of bone marrow obtained by bone marrow biopsy (often called trephine biopsy) and bone marrow aspiration. Bone marrow examination is used in the diagnosis of a number of conditi ...
following observations of the symptoms. Sometimes, blood tests may not show that a person has leukemia, especially in the early stages of the disease or during remission. A
lymph node biopsy Lymph node biopsy is a test in which a lymph node or a piece of a lymph node is removed for examination under a microscope (see: biopsy). The lymphatic system is made up of several lymph nodes connected by lymph vessels. The nodes produce white bl ...
can be performed to diagnose certain types of leukemia in certain situations. Following diagnosis, blood chemistry tests can be used to determine the degree of liver and kidney damage or the effects of chemotherapy on the person. When concerns arise about other damages due to leukemia, doctors may use an
X-ray An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10  picometers to 10  nanometers, corresponding to frequencies in the range 30&nb ...
,
MRI Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves ...
, or
ultrasound Ultrasound is sound waves with frequencies higher than the upper audible limit of human hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hear it. This limit varies ...
. These can potentially show leukemia's effects on such body parts as bones (X-ray), the brain (MRI), or the kidneys, spleen, and liver (ultrasound). CT scans can be used to check lymph nodes in the chest, though this is uncommon. Despite the use of these methods to diagnose whether or not a person has leukemia, many people have not been diagnosed because many of the symptoms are vague,
non-specific Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...
, and can refer to other diseases. For this reason, the American Cancer Society estimates that at least one-fifth of the people with leukemia have not yet been diagnosed.


Treatment

Most forms of leukemia are treated with pharmaceutical
medication A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy ( pharmacotherapy) is an important part of the medical field and ...
, typically combined into a multi-drug
chemotherapy regimen A chemotherapy regimen is a regimen for chemotherapy, defining the drugs to be used, their dosage, the frequency and duration of treatments, and other considerations. In modern oncology, many regimens combine several chemotherapy drugs in combina ...
. Some are also treated with
radiation therapy Radiation therapy or radiotherapy, often abbreviated RT, RTx, or XRT, is a therapy using ionizing radiation, generally provided as part of cancer treatment to control or kill malignant cells and normally delivered by a linear accelerator. Radi ...
. In some cases, a
bone marrow transplant Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood in order to replicate inside of a patient and to produce ...
is effective.


Acute lymphoblastic

Management of ALL is directed towards control of bone marrow and systemic (whole-body) disease. Additionally, treatment must prevent leukemic cells from spreading to other sites, particularly the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
(CNS) e.g. monthly lumbar punctures. In general, ALL treatment is divided into several phases: * ''Induction chemotherapy'' to bring about bone marrow remission. For adults, standard induction plans include
prednisone Prednisone is a glucocorticoid medication mostly used to suppress the immune system and decrease inflammation in conditions such as asthma, COPD, and rheumatologic diseases. It is also used to treat high blood calcium due to cancer and ad ...
,
vincristine Vincristine, also known as leurocristine and marketed under the brand name Oncovin among others, is a chemotherapy medication used to treat a number of types of cancer. This includes acute lymphocytic leukemia, acute myeloid leukemia, Hodgkin's ...
, and an
anthracycline Anthracyclines are a class of drugs used in cancer chemotherapy that are extracted from ''Streptomyces'' bacterium. These compounds are used to treat many cancers, including leukemias, lymphomas, breast, stomach, uterine, ovarian, bladder canc ...
drug; other drug plans may include L-asparaginase or cyclophosphamide. For children with low-risk ALL, standard therapy usually consists of three drugs (prednisone, L-asparaginase, and vincristine) for the first month of treatment. * ''Consolidation therapy'' or ''intensification therapy'' to eliminate any remaining leukemia cells. There are many different approaches to consolidation, but it is typically a high-dose, multi-drug treatment that is undertaken for a few months. People with low- to average-risk ALL receive therapy with
antimetabolite An antimetabolite is a chemical that inhibits the use of a metabolite, which is another chemical that is part of normal metabolism. Such substances are often similar in structure to the metabolite that they interfere with, such as the antifolate ...
drugs such as methotrexate and 6-mercaptopurine (6-MP). People who are high-risk receive higher drug doses of these drugs, plus additional drugs. * ''CNS prophylaxis'' (preventive therapy) to stop cancer from spreading to the brain and nervous system in high-risk people. Standard
prophylaxis Preventive healthcare, or prophylaxis, consists of measures taken for the purposes of disease prevention.Hugh R. Leavell and E. Gurney Clark as "the science and art of preventing disease, prolonging life, and promoting physical and mental hea ...
may include radiation of the head and/or drugs delivered directly into the spine. * ''Maintenance treatments'' with chemotherapeutic drugs to prevent disease recurrence once remission has been achieved. Maintenance therapy usually involves lower drug doses and may continue for up to three years. * Alternatively, '' allogeneic bone marrow transplantation'' may be appropriate for high-risk or relapsed people.


Chronic lymphocytic


Decision to treat

Hematologists base CLL treatment on both the stage and symptoms of the individual person. A large group of people with CLL have low-grade disease, which does not benefit from treatment. Individuals with CLL-related complications or more advanced disease often benefit from treatment. In general, the indications for treatment are: * Falling
hemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyt ...
or
platelet Platelets, also called thrombocytes (from Greek θρόμβος, "clot" and κύτος, "cell"), are a component of blood whose function (along with the coagulation factors) is to react to bleeding from blood vessel injury by clumping, thereby i ...
count * Progression to a later stage of disease * Painful, disease-related overgrowth of lymph nodes or
spleen The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes .
* An increase in the rate of
lymphocyte A lymphocyte is a type of white blood cell (leukocyte) in the immune system of most vertebrates. Lymphocytes include natural killer cells (which function in cell-mediated, cytotoxic innate immunity), T cells (for cell-mediated, cytotoxic ad ...
production


Treatment approach

Most CLL cases are incurable by present treatments, so treatment is directed towards suppressing the disease for many years, rather than curing it. The primary chemotherapeutic plan is
combination In mathematics, a combination is a selection of items from a set that has distinct members, such that the order of selection does not matter (unlike permutations). For example, given three fruits, say an apple, an orange and a pear, there are th ...
chemotherapy with chlorambucil or cyclophosphamide, plus a corticosteroid such as
prednisone Prednisone is a glucocorticoid medication mostly used to suppress the immune system and decrease inflammation in conditions such as asthma, COPD, and rheumatologic diseases. It is also used to treat high blood calcium due to cancer and ad ...
or
prednisolone Prednisolone is a steroid medication used to treat certain types of allergies, inflammatory conditions, autoimmune disorders, and cancers. Some of these conditions include adrenocortical insufficiency, high blood calcium, rheumatoid arthr ...
. The use of a corticosteroid has the additional benefit of suppressing some related autoimmune diseases, such as immunohemolytic anemia or immune-mediated thrombocytopenia. In resistant cases, single-agent treatments with nucleoside drugs such as fludarabine, pentostatin, or
cladribine Cladribine, sold under the brand name Leustatin, among others, is a medication used to treat hairy cell leukemia (leukemic reticuloendotheliosis) and B-cell chronic lymphocytic leukemia. Cladribine, sold under the brand name Mavenclad, is indicat ...
may be successful. Younger and healthier people may choose
allogeneic Allotransplant (''allo-'' meaning "other" in Greek) is the transplantation of cells, tissues, or organs to a recipient from a genetically non-identical donor of the same species. The transplant is called an allograft, allogeneic transplant, o ...
or
autologous Autotransplantation is the transplantation of organs, tissues, or even particular proteins from one part of the body to another in the same person ('' auto-'' meaning "self" in Greek). The autologous tissue (also called autogenous, autogenei ...
bone marrow transplantation Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood in order to replicate inside of a patient and to produce ...
in the hope of a permanent cure.


Acute myelogenous

Many different anti-cancer drugs are effective for the treatment of AML. Treatments vary somewhat according to the age of the person and according to the specific subtype of AML. Overall, the strategy is to control bone marrow and systemic (whole-body) disease, while offering specific treatment for the central nervous system (CNS), if involved. In general, most oncologists rely on combinations of drugs for the initial, ''induction phase'' of chemotherapy. Such combination chemotherapy usually offers the benefits of early remission and a lower risk of disease resistance. ''Consolidation'' and ''maintenance'' treatments are intended to prevent disease recurrence. Consolidation treatment often entails a repetition of induction chemotherapy or the intensification of chemotherapy with additional drugs. By contrast, maintenance treatment involves drug doses that are lower than those administered during the induction phase.


Chronic myelogenous

There are many possible treatments for CML, but the standard of care for newly diagnosed people is imatinib (Gleevec) therapy. Compared to most anti-cancer drugs, it has relatively few side effects and can be taken orally at home. With this drug, more than 90% of people will be able to keep the disease in check for at least five years, so that CML becomes a chronic, manageable condition. In a more advanced, uncontrolled state, when the person cannot tolerate imatinib, or if the person wishes to attempt a permanent cure, then an allogeneic bone marrow transplantation may be performed. This procedure involves high-dose chemotherapy and radiation followed by infusion of bone marrow from a compatible donor. Approximately 30% of people die from this procedure.


Hairy cell

Decision to treat
People with hairy cell leukemia who are symptom-free typically do not receive immediate treatment. Treatment is generally considered necessary when the person shows signs and symptoms such as low blood cell counts (e.g., infection-fighting neutrophil count below 1.0 K/µL), frequent infections, unexplained bruises, anemia, or fatigue that is significant enough to disrupt the person's everyday life. Typical treatment approach
People who need treatment usually receive either one week of
cladribine Cladribine, sold under the brand name Leustatin, among others, is a medication used to treat hairy cell leukemia (leukemic reticuloendotheliosis) and B-cell chronic lymphocytic leukemia. Cladribine, sold under the brand name Mavenclad, is indicat ...
, given daily by intravenous infusion or a simple injection under the skin, or six months of pentostatin, given every four weeks by intravenous infusion. In most cases, one round of treatment will produce a prolonged remission. Other treatments include
rituximab Rituximab, sold under the brand name Rituxan among others, is a monoclonal antibody medication used to treat certain autoimmune diseases and types of cancer. It is used for non-Hodgkin lymphoma, chronic lymphocytic leukemia (in non-geriatric pa ...
infusion or self-injection with
Interferon-alpha The type-I interferons (IFN) are cytokines which play essential roles in inflammation, immunoregulation, tumor cells recognition, and T-cell responses. In the human genome, a cluster of thirteen functional IFN genes is located at the 9p21.3 cyt ...
. In limited cases, the person may benefit from ''
splenectomy A splenectomy is the surgical procedure that partially or completely removes the spleen. The spleen is an important organ in regard to immunological function due to its ability to efficiently destroy encapsulated bacteria. Therefore, removal of ...
'' (removal of the spleen). These treatments are not typically given as the first treatment because their success rates are lower than cladribine or pentostatin.


T-cell prolymphocytic

Most people with T-cell prolymphocytic leukemia, a rare and aggressive leukemia with a median survival of less than one year, require immediate treatment. T-cell prolymphocytic leukemia is difficult to treat, and it does not respond to most available chemotherapeutic drugs. Many different treatments have been attempted, with limited success in certain people: purine analogues (pentostatin, fludarabine, cladribine), chlorambucil, and various forms of combination chemotherapy (cyclophosphamide, doxorubicin, vincristine, prednisone CHOP, cyclophosphamide, vincristine, prednisone OP vincristine, doxorubicin, prednisone, etoposide, cyclophosphamide, bleomycin VAPEC-B).
Alemtuzumab Alemtuzumab, sold under the brand names Campath and Lemtrada among others, is a medication used to treat chronic lymphocytic leukemia (CLL) and multiple sclerosis. In CLL, it has been used as both a first line and second line treatment. In MS it ...
(Campath), a
monoclonal antibody A monoclonal antibody (mAb, more rarely called moAb) is an antibody produced from a cell Lineage made by cloning a unique white blood cell. All subsequent antibodies derived this way trace back to a unique parent cell. Monoclonal antibodies ...
that attacks white blood cells, has been used in treatment with greater success than previous options. Some people who successfully respond to treatment also undergo stem cell transplantation to consolidate the response.


Juvenile myelomonocytic

Treatment for juvenile myelomonocytic leukemia can include
splenectomy A splenectomy is the surgical procedure that partially or completely removes the spleen. The spleen is an important organ in regard to immunological function due to its ability to efficiently destroy encapsulated bacteria. Therefore, removal of ...
,
chemotherapy Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemothe ...
, and
bone marrow transplantation Hematopoietic stem-cell transplantation (HSCT) is the transplantation of multipotent hematopoietic stem cells, usually derived from bone marrow, peripheral blood, or umbilical cord blood in order to replicate inside of a patient and to produce ...
.


Teeth

Before dental work it is recommended that the person's physician be consulted. Dental work is recommended before chemotherapy or radiation therapy. Those in remission can be treated per normal.


Prognosis

The success of treatment depends on the type of leukemia and the age of the person. Outcomes have improved in the developed world. The average
five-year survival rate The five-year survival rate is a type of survival rate for estimating the prognosis of a particular disease, normally calculated from the point of diagnosis. Lead time bias from earlier diagnosis can affect interpretation of the five-year surviva ...
is 65% in the United States. In children under 15, the five-year survival rate is greater (60 to 85%), depending on the type of leukemia. In children with acute leukemia who are cancer-free after five years, the cancer is unlikely to return. Outcomes depend on whether it is acute or chronic, the specific abnormal white blood cell type, the presence and severity of
anemia Anemia or anaemia (British English) is a blood disorder in which the blood has a reduced ability to carry oxygen due to a lower than normal number of red blood cells, or a reduction in the amount of hemoglobin. When anemia comes on slowly, t ...
or
thrombocytopenia Thrombocytopenia is a condition characterized by abnormally low levels of platelets, also known as thrombocytes, in the blood. It is the most common coagulation disorder among intensive care patients and is seen in a fifth of medical patients a ...
, the degree of tissue abnormality, the presence of
metastasis Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then ...
and lymph node and bone marrow infiltration, the availability of therapies and the skills of the health care team. Treatment outcomes may be better when people are treated at larger centers with greater experience.


Epidemiology

In 2010, globally, approximately 281,500 people died of leukemia. In 2000, approximately 256,000 children and adults around the world developed a form of leukemia, and 209,000 died from it. This represents about 3% of the almost seven million deaths due to cancer that year, and about 0.35% of all deaths from any cause. Of the sixteen separate sites the body compared, leukemia was the 12th most common class of
neoplastic disease A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...
and the 11th most common cause of cancer-related death. Leukemia occurs more commonly in the
developed world A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...
.


United States

About 245,000 people in the United States are affected with some form of leukemia, including those that have achieved remission or cure. Rates from 1975 to 2011 have increased by 0.7% per year among children. Approximately 44,270 new cases of leukemia were diagnosed in the year 2008 in the US. This represents 2.9% of all cancers (excluding simple basal cell and squamous cell skin cancers) in the United States, and 30.4% of all
blood cancer Tumors of the hematopoietic and lymphoid tissues (American English) or tumours of the haematopoietic and lymphoid tissues (British English) are tumors that affect the blood, bone marrow, lymph, and lymphatic system. Because these tissues are all ...
s. Among children with some form of cancer, about a third have a type of leukemia, most commonly acute lymphoblastic leukemia. A type of leukemia is the second most common form of cancer in infants (under the age of 12 months) and the most common form of cancer in older children. Boys are somewhat more likely to develop leukemia than girls, and white American children are almost twice as likely to develop leukemia than black American children. Only about 3% cancer diagnoses among adults are for leukemias, but because cancer is much more common among adults, more than 90% of all leukemias are diagnosed in adults.
Race Race, RACE or "The Race" may refer to: * Race (biology), an informal taxonomic classification within a species, generally within a sub-species * Race (human categorization), classification of humans into groups based on physical traits, and/or s ...
is a
risk factor In epidemiology, a risk factor or determinant is a variable associated with an increased risk of disease or infection. Due to a lack of harmonization across disciplines, determinant, in its more widely accepted scientific meaning, is often ...
in the United States.
Hispanic The term ''Hispanic'' ( es, hispano) refers to people, cultures, or countries related to Spain, the Spanish language, or Hispanidad. The term commonly applies to countries with a cultural and historical link to Spain and to viceroyalties forme ...
s, especially those under the age of 20, are at the highest risk for leukemia, while
whites White is a racialized classification of people and a skin color specifier, generally used for people of European origin, although the definition can vary depending on context, nationality, and point of view. Description of populations as ...
, Native Americans, Asian Americans, and Alaska Natives are at higher risk than African Americans. More men than women are diagnosed with leukemia and die from the disease. Around 30 percent more men than women have leukemia.


UK

Overall, leukemia is the eleventh most common cancer in the UK (around 8,600 people were diagnosed with the disease in 2011), and it is the ninth most common cause of cancer death (around 4,800 people died in 2012).


History

Leukemia was first described by anatomist and surgeon Alfred-Armand-Louis-Marie Velpeau in 1827. A more complete description was given by pathologist
Rudolf Virchow Rudolf Ludwig Carl Virchow (; or ; 13 October 18215 September 1902) was a German physician, anthropologist, pathologist, prehistorian, biologist, writer, editor, and politician. He is known as "the father of modern pathology" and as the founder ...
in 1845. Around ten years after Virchow's findings, pathologist Franz Ernst Christian Neumann found that the bone marrow of a deceased person with leukemia was colored "dirty green-yellow" as opposed to the normal red. This finding allowed Neumann to conclude that a bone marrow problem was responsible for the abnormal blood of people with leukemia. By 1900, leukemia was viewed as a family of diseases as opposed to a single disease. By 1947, Boston pathologist
Sidney Farber Sidney Farber (September 30, 1903 – March 30, 1973) was an American pediatric pathologist. He is regarded as the father of modern chemotherapy for his work using folic acid antagonists to combat leukemia, which led to the development of other c ...
believed from past experiments that
aminopterin Aminopterin (or 4-aminopteroic acid), the 4-amino derivative of folic acid, is an antineoplastic drug with immunosuppressive properties often used in chemotherapy. Aminopterin is a synthetic derivative of pterin. Aminopterin works as an enzyme inh ...
, a folic acid mimic, could potentially cure leukemia in children. The majority of the children with ALL who were tested showed signs of improvement in their bone marrow, but none of them was actually cured. This, however, led to further experiments. In 1962, researchers Emil J. Freireich, Jr. and Emil Frei III used combination chemotherapy to attempt to cure leukemia. The tests were successful with some people surviving long after the tests.


Etymology

Observing an abnormally large number of white blood cells in a blood sample from a person, Virchow called the condition ''Leukämie'' in German, which he formed from the two
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
words ''leukos'' ( λευκός), meaning "white", and ''haima'' ( αἷμα), meaning "blood".


Society and culture

According to Susan Sontag, leukemia was often romanticized in 20th-century fiction, portrayed as a joy-ending, clean disease whose fair, innocent and gentle victims die young or at the wrong time. As such, it was the cultural successor to
tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, i ...
, which held this cultural position until it was discovered to be an infectious disease. The 1970 romance novel '' Love Story'' is an example of this romanticization of leukemia. In the United States, around $5.4 billion is spent on treatment a year.


Research directions

Significant research into the causes, prevalence, diagnosis, treatment, and prognosis of leukemia is being performed. Hundreds of clinical trials are being planned or conducted at any given time. Studies may focus on effective means of treatment, better ways of treating the disease, improving the quality of life for people, or appropriate care in remission or after cures. In general, there are two types of leukemia research: clinical or
translational research Translational research (also called translation research, translational science, or, when the context is clear, simply translation) is research aimed at translating (converting) results in basic research into results that directly benefit humans. ...
and
basic research Basic research, also called pure research or fundamental research, is a type of scientific research with the aim of improving scientific theories for better understanding and prediction of natural or other phenomena. In contrast, applied rese ...
. Clinical/translational research focuses on studying the disease in a defined and generally immediately applicable way, such as testing a new drug in people. By contrast, basic science research studies the disease process at a distance, such as seeing whether a suspected carcinogen can cause leukemic changes in isolated cells in the laboratory or how the DNA changes inside leukemia cells as the disease progresses. The results from basic research studies are generally less immediately useful to people with the disease. Treatment through
gene therapy Gene therapy is a medical field which focuses on the genetic modification of cells to produce a therapeutic effect or the treatment of disease by repairing or reconstructing defective genetic material. The first attempt at modifying human DN ...
is currently being pursued. One such approach used genetically modified
T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...
s, known as chimeric antigen receptor T cells (CAR-T cells), to attack cancer cells. In 2011, a year after treatment, two of the three people with advanced chronic lymphocytic leukemia were reported to be cancer-free and in 2013, three of five subjects who had acute lymphocytic leukemia were reported to be in remission for five months to two years. Subsequent studies with a variety of CAR-T types continue to be promising. As of 2018, two CAR-T therapies have been approved by the
Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a List of United States federal agencies, federal agency of the United States Department of Health and Human Services, Department of Health and Human Services. The FDA is respon ...
. CAR-T treatment has significant side effects, and loss of the
antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune respons ...
targeted by the CAR-T cells is a common mechanism for relapse. The stem cells that cause different types of leukemia are also being researched.


Pregnancy

Leukemia is rarely associated with pregnancy, affecting only about 1 in 10,000 pregnant women. How it is handled depends primarily on the type of leukemia. Nearly all leukemias appearing in pregnant women are acute leukemias. Acute leukemias normally require prompt, aggressive treatment, despite significant risks of
pregnancy loss Pregnancy loss is the death of an embryo or fetus. It may include any of the following: ;Unintentional pregnancy loss: * Miscarriage ** Blighted ovum ** Ectopic pregnancy * Stillbirth * Toxic abortion, caused by pollution or chemical exposures ;P ...
and
birth defects A birth defect, also known as a congenital disorder, is an abnormal condition that is present at birth regardless of its cause. Birth defects may result in disabilities that may be physical, intellectual, or developmental. The disabilities can ...
, especially if chemotherapy is given during the developmentally sensitive
first trimester Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occurs by sexual intercourse, but ...
. Chronic myelogenous leukemia can be treated with relative safety at any time during pregnancy with
Interferon-alpha The type-I interferons (IFN) are cytokines which play essential roles in inflammation, immunoregulation, tumor cells recognition, and T-cell responses. In the human genome, a cluster of thirteen functional IFN genes is located at the 9p21.3 cyt ...
hormones. Treatment for chronic lymphocytic leukemias, which are rare in pregnant women, can often be postponed until after the end of the pregnancy.


See also

* Acute erythroid leukemia *
Antileukemic drug Antileukemic drugs, anticancer drugs that are used to treat one or more types of leukemia, include: *6-Mercaptopurine *6-Thioguanine * Arsenic trioxide * Asparaginase * Cladribine *Clofarabine *Cyclophosphamide * Cytosine arabinoside * Dasatinib ...
s, medications used to kill leukemia cells * Cancer-related fatigue *
Hematologic disease Hematologic diseases are disorders which primarily affect the blood & blood-forming organs. Hematologic diseases include rare genetic disorders, anemia, HIV, sickle cell disease & complications from chemotherapy or transfusions. Myeloid * Hemog ...
s, the large class of blood-related disorders, including leukemia * Multiple myeloma


References


External links

*
Leukaemia information
from
Cancer Research UK Cancer Research UK (CRUK) is the world's largest independent cancer research organization. It is registered as a charity in the United Kingdom and Isle of Man, and was formed on 4 February 2002 by the merger of The Cancer Research Campaign and t ...
{{Authority control Lymphatic vessel diseases Wikipedia medicine articles ready to translate Articles containing video clips