Diagnosis

Controversy exists over the best approach for patients with Stage II cancers when the sentinel node test has found no evidence of cancer. These melanomas are usually between 1 mm and 4 mm thick, and tumors at this stage carry a risk for sending microscopic cancer cells out into the lymph system unnoticed. However, new methods of examining sentinel lymph node biopsies are improving the ability to identify these cells, called micrometastases. Still, in such cases, removal of lymph nodes would probably have no impact on survival.

Biologic markers in blood tests may also prove to identify microscopic cancers if sentinel node biopsy results are uncertain.

Secondary Tests

If melanoma has been diagnosed, the doctor will perform others tests to see if the cancer has spread. They typically include the following:

• A chest x-ray.
• Blood tests that show high levels of lactate dehydrogenase suggest metastasis.
• Blood tests to assess liver function and other factors to help determine specific sites where the cancer may have spread.
• Advanced imaging techniques, such as computed tomography (CT) or positron emission tomography (PET), may also be used. PET is particularly accurate. One study reported that PET was able to diagnose melanoma that had spread even when other tests, including CT, did not. PET can also be very accurate for identifying recurrent melanomas.

Biologic Markers for Metastasis

Researchers are continually looking for other biologic factors, or markers, that would indicate whether the cancer had metastasized (even if sentinel node biopsies are negative). They also might suggest the severity of the cancer, which would help determine whether treatments should be more or less aggressive. A number of proteins and other factors detected in blood tests are showing promise as markers for microscopic metastasis. Examples include antibodies to MART-1, Melan-A, tyrosinase, and microphthalmia transcription factor (Mitf). Combinations of some of these factors may improve detection rates.

Risk Factors for Determining Prognosis

To reach a prognosis, other factors in addition to staging must be considered such as gender, age, and location of the melanoma. All cases are unique, however, and the presence of any of these factors should not discourage people from seeking all possible treatment options.

• Age. Patients older than 50 generally have the worst prognosis, perhaps because they tend to wait to see the doctor and thus have the thickest lesions.
• Gender. Although women and men fare equally well in the first 2 years after diagnosis, women appear to do a bit better after that time, particularly younger women. Prepubescent girls have a poorer prognosis than boys do (although it is very rare in children). This suggests, but does not prove, that estrogen may have some protective properties. The difference in gender may simply be due to women giving more attention to their skin.
• Melanoma Characteristics. Thick melanomas, those that are ulcerated (in which skin layers over the tumor appear indistinct on pathologic examination), and those that have invaded blood vessels tend to have a worse prognosis.
• Original Site. Patients with melanomas that arise within preexisting moles may fare better than those with new lesions. Some studies indicate that melanomas furthest away from the trunk, particularly the feet, were associated with poorer survival, but this may be because such areas are less likely to be observed and so such melanomas tend to be diagnosed at a late stage.
• Metastasis. Survival rates are worse if the cancer has spread, particularly to the gastrointestinal tract, liver, or lung. In any case, the more sites that the cancer has spread to, the poorer the prognosis.
• Regression. In some people, melanomas spontaneously stop growing for a time and may actually shrink in size, which is a favorable sign.