A cure is a substance or procedure that resolves a medical condition. This may include a
medication
Medication (also called medicament, medicine, pharmaceutical drug, medicinal product, medicinal drug or simply drug) is a drug used to medical diagnosis, diagnose, cure, treat, or preventive medicine, prevent disease. Drug therapy (pharmaco ...
, a
surgical operation
Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery ...
, a lifestyle change, or even a philosophical shift that alleviates a person's suffering or achieves a state of healing. The medical condition can be a
disease
A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...
,
mental illness
A mental disorder, also referred to as a mental illness, a mental health condition, or a psychiatric disability, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. A mental disorder is ...
,
genetic disorder
A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosome abnormality. Although polygenic disorders ...
, or a condition considered socially undesirable, such as
baldness
Hair loss, also known as alopecia or baldness, refers to a loss of hair from part of the head or body. Typically at least the head is involved. The severity of hair loss can vary from a small area to the entire body. Inflammation or scarring ...
or insufficient breast tissue.
An incurable disease is not necessarily a
terminal illness
Terminal illness or end-stage disease is a disease that cannot be cured or adequately treated and is expected to result in the death of the patient. This term is more commonly used for progressive diseases such as cancer, rather than fatal injur ...
, and conversely, a curable illness can still be fatal.
The cure fraction or cure rate—the proportion of people with a disease who are cured by a given treatment—is determined by comparing
disease-free survival
Survival rate is a part of survival analysis. It is the proportion of people in a study or treatment group still alive at a given period of time after diagnosis. It is a method of describing prognosis in certain disease conditions, and can be use ...
in treated individuals against a matched control group without the disease.
Another method for determining the cure fraction and/or "cure time" involves measuring when the hazard rate in a diseased group returns to the hazard rate observed in the general population.
The concept of a cure inherently implies the permanent resolution of a specific instance of a disease. For example, a person who recovers from the
common cold
The common cold, or the cold, is a virus, viral infectious disease of the upper respiratory tract that primarily affects the Respiratory epithelium, respiratory mucosa of the human nose, nose, throat, Paranasal sinuses, sinuses, and larynx. ...
is considered ''cured'', even though they may contract another cold in the future. Conversely, a person who effectively manages a disease like
diabetes mellitus
Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or th ...
to prevent undesirable symptoms without permanently eliminating it is not considered cured.
Related concepts with potentially differing meanings include ''response'', ''remission'', and ''recovery''.
Statistical model
In complex diseases like cancer, researchers use statistical comparisons of
disease-free survival
Survival rate is a part of survival analysis. It is the proportion of people in a study or treatment group still alive at a given period of time after diagnosis. It is a method of describing prognosis in certain disease conditions, and can be use ...
(DFS) between patients and matched, healthy control groups. This approach equates indefinite remission with a cure.
The
Kaplan-Meier estimator is commonly used for this comparison.
The simplest cure rate model was published by
Joseph Berkson
Joseph Berkson (14 May 1899 – 12 September 1982) was trained as a physicist (BSc 1920, College of City of New York CNY M.A., 1922, Columbia), physician (M.D., 1927, Johns Hopkins), and statistician (Dr.Sc., 1928, Johns Hopkins).O'Fallon WM (19 ...
and
Robert P. Gage in 1952.
In this model, survival at any given time equals the sum of those who are cured and those who are not cured but have not yet died or, in diseases with asymptomatic remissions, have not yet experienced a recurrence of signs and symptoms. Once all non-cured individuals have died or experienced disease recurrence, only the permanently cured population members remain, and the DFS curve becomes flat. The earliest point at which the curve flattens indicates when all remaining disease-free survivors are considered permanently cured. If the curve never flattens, the disease is formally considered incurable (with existing treatments).
The
Berkson and Gage equation is