In
medicine
Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pract ...
, Breslow's depth was used as a
prognostic factor
Prognosis (Greek: πρόγνωσις "fore-knowing, foreseeing") is a medical term for predicting the likely or expected development of a disease, including whether the signs and symptoms will improve or worsen (and how quickly) or remain stable ...
in
melanoma
Melanoma, also redundantly known as malignant melanoma, is a type of skin cancer that develops from the pigment-producing cells known as melanocytes. Melanomas typically occur in the skin, but may rarely occur in the mouth, intestines, or eye ( ...
of the
skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...
. It is a description of how deeply tumor cells have invaded. Currently, the standard Breslow's depth has been replaced by the AJCC depth, in the
AJCC staging system of melanoma. Originally, Breslow's depth was divided into 5 stages.
Classification
History
Depth of invasion was first reported as a prognostic factor in melanoma by the
pathologist
Pathology is the study of the causal, causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when us ...
Alexander Breslow, M.D. at George Washington University in 1970.
[ In recognition of his contribution, the depth of invasion of melanoma is referred to by the ]eponym
An eponym is a person, a place, or a thing after whom or which someone or something is, or is believed to be, named. The adjectives which are derived from the word eponym include ''eponymous'' and ''eponymic''.
Usage of the word
The term ''epon ...
''Breslow's depth''.
Subsequent studies confirmed and refined the role of depth of invasion in the prognosis of malignant melanoma. Currently, Breslow's depth is included in the AJCC {{Short description, Organization standardising cancer staging
The American Joint Committee on Cancer (AJCC) is an organization best known for defining and popularizing cancer staging standards, officially the AJCC staging system.
The American Joi ...
staging
Staging may refer to:
Computing
* Staging (cloud computing), a process used to assemble, test, and review a new solution before it is moved into production and the existing solution is decommissioned
* Staging (data), intermediately storing data ...
guidelines for melanoma as a major prognostic factor.
Measurement
Tumor depth is most accurately measured by evaluating the entire tumor via an excisional biopsy
A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a dise ...
. Determination from specimens obtained using other biopsy
A biopsy is a medical test commonly performed by a surgeon, interventional radiologist, or an interventional cardiologist. The process involves extraction of sample cells or tissues for examination to determine the presence or extent of a diseas ...
techniques, such as a wedge or punch biopsy, are less accurate. Tumor depth cannot be calculated from a shave biopsy that only contains a portion of the tumor because it leads to an underestimation of its thickness.
Breslow's depth is determined by using an ocular micrometer at a right angle
In geometry and trigonometry, a right angle is an angle of exactly 90 Degree (angle), degrees or radians corresponding to a quarter turn (geometry), turn. If a Line (mathematics)#Ray, ray is placed so that its endpoint is on a line and the ad ...
to the skin to directly measure the depth to which tumor cells
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 ...
have invaded the skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...
. Breslow's depth is measured from the granular layer of the epidermis
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rele ...
down to the deepest point of invasion (sometimes involving detached nests of cells).
Prognostic importance
Tumor depth is one of the cornerstones of the current AJCC {{Short description, Organization standardising cancer staging
The American Joint Committee on Cancer (AJCC) is an organization best known for defining and popularizing cancer staging standards, officially the AJCC staging system.
The American Joi ...
TNM staging
The TNM Classification of Malignant Tumors (TNM) is a globally recognised standard for classifying the extent of spread of cancer. It is a classification system of the anatomical extent of tumor cancers. It has gained wide international acceptance ...
of malignant melanoma. A large study validated the importance of tumor depth (but not Breslow's original description) as one of the three most important prognostic factors in melanoma (the others being T stage and ulceration). Breslow's depth also accurately predicted the risk for lymph node
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 ...
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, ...
, with deeper tumors being more likely to involve the nodes.
The above studies showed that depth was a continuous variable correlating with prognosis. However, for staging purposes, the most recent AJCC guidelines use cutoffs of 1 mm, 2 mm, and 4 mm to divide patients into stages.
Survival figures from British Association of Dermatologist Guidelines, 2002
Clark's level
Clark's level is a related staging system
Cancer staging is the process of determining the extent to which a cancer has developed by growing and spreading. Contemporary practice is to assign a number from I to IV to a cancer, with I being an isolated cancer and IV being a cancer that ha ...
, used in conjunction with Breslow's depth, which describes the level of anatomical invasion of the melanoma in the skin.[Weedon, D. Skin pathology. 2nd Edition. 2002. Sydney: Churchill-Livingstone. ] Clark's level was the primary factor in earlier AJCC staging schemae for melanoma. However, with further study, it has been shown that Clark's level has a lower predictive value, is less reproducible, and is more operator-dependent as compared with Breslow's depth. Thus, in the current (2010) AJCC staging system, Clark's level has prognostic significance only in patients with very thin (Breslow depth <1 mm) melanomas.
Five anatomical levels are recognized, and higher levels have worsening prognostic implications. These levels are:
*Level 1: Melanoma confined to the epidermis
The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. The epidermis layer provides a barrier to infection from environmental pathogens and regulates the amount of water rele ...
(melanoma in situ)
*Level 2: Invasion into the papillary dermis
The dermis or corium is a layer of skin between the epidermis (with which it makes up the cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from stress and strain. It is divided in ...
*Level 3: Invasion to the junction of the papillary
Papilla (Latin, 'nipple') or papillae may refer to:
In animals
* Papilla (fish anatomy), in the mouth of fish
* Basilar papilla, a sensory organ of lizards, amphibians and fish
* Dental papilla, in a developing tooth
* Dermal papillae, part of ...
and reticular dermis
The dermis or corium is a layer of skin between the epidermis (with which it makes up the cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from stress and strain. It is divided in ...
*Level 4: Invasion into the reticular dermis
The dermis or corium is a layer of skin between the epidermis (with which it makes up the cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from stress and strain. It is divided in ...
*Level 5: Invasion into the subcutaneous fat[
]
See also
* ABCD guideline
*American Joint Committee on Cancer {{Short description, Organization standardising cancer staging
The American Joint Committee on Cancer (AJCC) is an organization best known for defining and popularizing cancer staging standards, officially the AJCC staging system.
The American Joi ...
(AJCC)
*Cancer staging
Cancer staging is the process of determining the extent to which a cancer has developed by growing and spreading. Contemporary practice is to assign a number from I to IV to a cancer, with I being an isolated cancer and IV being a cancer that ha ...
References
{{Reflist
External links
Melanoma Staging Systems
National Cancer Institute. A resource on Clark's levels and Breslow's depth.
Cancer staging
Dermatologic terminology
Histopathology
Melanocytic nevi and neoplasms