Melanoma

http://en.wikipedia.org/wiki/Melanoma
[excerpt]
Prognostic Factors

See also: Breslow's depth

Black, irregularly shaped, uniformly brown pigmented nevus on a
19-year-old man's right cheek. The Breslow index measured 2.88 mm, and a
thorough medical evaluation revealed no evidence of metastases. The scar
was reexcised with a 2 cm margin, and the skin was repaired with a graft.
Black, irregularly shaped, uniformly brown pigmented nevus on a
19-year-old man's right cheek. The Breslow index measured 2.88 mm, and a
thorough medical evaluation revealed no evidence of metastases. The scar
was reexcised with a 2 cm margin, and the skin was repaired with a graft.

Features that affect prognosis are tumor thickness in millimeters
(Breslow's depth), depth related to skin structures (Clark level), type of
melanoma, presence of ulceration, presence of lymphatic/perineural
invasion, presence of tumor infiltrating lymphocytes (if present,
prognosis is better), location of lesion, presence of satellite lesions,
and presence of regional or distant metastasis.[28]

Certain types of melanoma have worse prognoses but this is explained by
their thickness. Interestingly, less invasive melanomas even with lymph
node metastases carry a better prognosis than deep melanomas without
regional metastasis at time of staging. Local recurrences tend to behave
similarly to a primary unless they are at the site of a wide local
excision (as opposed to a staged excision or punch/shave excision) since
these recurrences tend to indicate lymphatic invasion.

When melanomas have spread to the lymph nodes, one of the most important
factors is the number of nodes with malignancy. Extent of malignancy
within a node is also important; micrometastases in which malignancy is
only microscopic have a more favorable prognosis than macrometastases. In
some cases micrometastases may only be detected by special staining, and
if malignancy is only detectable by a rarely-employed test known as
polymerase chain reaction (PCR), the prognosis is better. Macrometastases
in which malignancy is clinically apparent (in some cases cancer
completely replaces a node) have a far worse prognosis, and if nodes are
matted or if there is extracapsular extension, the prognosis is still
worse.

When there is distant metastasis, the cancer is generally considered
incurable. The five year survival rate is less than 10%.[29] The median
survival is 6 to 12 months. Treatment is palliative, focusing on
life-extension and quality of life. In some cases, patients may live many
months or even years with metastatic melanoma (depending on the
aggressiveness of the treatment). Metastases to skin and lungs have a
better prognosis. Metastases to brain, bone and liver are associated with
a worse prognosis.

There is not enough definitive evidence to adequately stage, and thus give
a prognosis for ocular melanoma and melanoma of soft parts, or mucosal
melanoma (e.g. rectal melanoma), although these tend to metastasize more
easily. Even though regression may increase survival, when a melanoma has
regressed, it is impossible to know its original size and thus the
original tumor is often worse than a pathology report might indicate.

Staging...see the rest

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