Melanoma

Melanoma is a deadly skin cancer. Skin cancers are subdivided into different kinds based on which skin cells they come from. Melanoma originates from pigmented cells (melanocytes) interspersed in the top layers of the skin. In contrast, non-melanoma skin cancers (basal cell carcinoma and squamous cell carcinoma) arise from keratinocytes (non-pigmented cells comprising the bulk of the very top layer of the skin). There is no relationship between melanoma and non-melanoma skin cancers.

Basal cell carcinoma and squamous cell carcinoma rarely metastasize (spread through the body). Melanoma metastasizes if not removed in time. Hence, it is the most dangerous skin cancer.

It appears that some melanomas grow quickly, invade the skin, and spread through the body fast. There are other melanomas which may stay in the top layer of the skin for decades and only then start invading. Yet, even thin melanomas can spread through the body and kill. A test to reliably distinguish between slow-growing melanomas with low immediate capacity for metastases and aggressive “fast killer” melanomas has not yet come to fruition. All melanomas are currently treated with the assumption that they can and will kill the patient unless removed.

About half of melanomas arise from pre-existing moles while the rest form anew. Light skinned individuals, those who have had intermittent sunburns, and patients with personal and family history of atypical moles and melanoma are at higher risk of developing melanoma.

Melanoma is diagnosed by sampling the skin (biopsy). Once the dermatopathologist establishes the diagnosis of melanoma on a biopsy, he or she also notes the level of invasion into the skin (using the Breslow thickness scale) measured in millimeters. This measurement specifies how deep the melanoma cells have spread into the skin. The Breslow scale is very helpful in the prognosis of a malignant melanoma. If the invasion into the skin is less than 1 mm, the chances of survival are excellent (up to 99% of patients are alive in 5 years). On the other side of the spectrum, deeply invasive melanomas (deeper than 4 mm) have a much worse prognosis and kill up to 50% of patients. Lesions with an invasion of between 1 and 4 mm have an intermediate prognosis (the survival rate is between 50 and 99 percent).

For most melanomas the main and only treatment is surgical excision. This is because most melanomas are thin and do not invade deeply. No additional testing (x-rays, blood work, CT scans, etc.) are needed for such thin melanomas. Additional testing is needed for patients with deeper melanomas and for those whose melanoma has spread to the lymph nodes.

For many patients with melanoma (mostly those with Breslow invasion of between 1 and 4 mm) an additional surgical procedure - sentinel node biopsy - is suggested. The procedure is performed in several stages. First, a radioactive dye is injected around the melanoma site. The lymph fluid carries the dye away from the tumor and to the nearest lymph nodes. The surgeon then uses a radiation detector to find the node or nodes with the highest concentration of radioactive dye. This node (called the sentinel node) is removed and sent for examination under the microscope. The specimen is checked for presence of cancer cells.

If cancer is detected during sentinel node biopsy, the treatment usually becomes more aggressive. Many more lymph nodes are removed. Sentinel node biopsy is generally not recommended for those with thin (under 1 mm in thickness) or thick (over 4 mm in thickness) melanomas. This procedure is controversial. Many dermatologists still believe that doing a sentinel node biopsy does not improve patients’ chances for survival. It appears though, that for most patients with intermediate melanomas this procedure is becoming the standard of care.

If melanoma invades the skin and then migrates to the internal organs or distant sites, the prognosis is very poor (only 6% of patients survive to the 5-year mark). The treatment of advanced melanoma is quite inadequate.

Anyone who has had a melanoma in the past needs a lifetime of follow up with a dermatologist for regular skin exams. The purpose of the exams is not only to detect a possible recurrence of the same melanoma, but also to monitor for the appearance of new melanomas. Monthly self-examinations and sun protection are also recommended.

Alexander Doctoroff, D.O., F.A.O.C.D. Assistant Chief of Dermatology, Veterans Administration Medical Center East Orange, New Jersey

Assistant Clinical Professor of Medicine, University of Medicine and Dentistry of New Jersey www.metropolitanderm.com