Melanoma

By Peter Galvin, MD

Melanoma is a type of skin cancer that affects the pigment-producing cells (melanocytes) of the skin. It accounts for only 1% of skin cancers but causes the majority of deaths from skin cancer, mostly because it is nearly the only skin cancer that is invasive (squamous cell carcinomas can be locally invasive but do not compare to the virulence of melanomas). In the U.S. in 2022, about 100,000 new cases of melanoma were diagnosed, and there were 7,650 deaths from melanoma. Melanomas commonly appear as dark brown or black, irregularly shaped marks that have a different appearance than a person’s other moles and freckles. They may contain a mix of light and dark colors and have jagged, asymmetrical borders. While most are tan or brown, some lack pigment and appear pink. They frequently change over time; they may grow in size, become more raised, develop color changes, and/or bleed. Although melanoma typically occurs on the skin, it may develop in other parts of the body such as the eye or mouth. They may also arise in areas of the skin that have had little to no sun exposure, like the bottom of the feet and groin.

Major risk factors for melanoma include older age, male sex, increased number of moles, lighter skin tone, having a family member with melanoma, and a history of extensive exposure to UV light from the sun and/or tanning beds. They may occur in younger people with darker skin tones. In these people, melanomas often develop in more commonly sun-protected areas like the palms and soles and may not be associated with UV exposure. The standard way to diagnose melanoma is with skin biopsy. Treatment usually involves surgical removal of the melanoma and a margin of surrounding normal skin (Mohs surgery). Immediate microscopic evaluation is performed to ensure that the entire lesion was removed, and the margins are free of tumor. If the melanoma has grown deeply into the skin, then local lymph node biopsy is performed. If melanoma is deep or present in the lymph nodes, then evaluation with imaging studies like MRI, CT, or PET scanning is done to look for distant spread (metastatic disease). Advanced melanomas or melanomas not amenable to surgical removal may be treated with systemic medications including chemotherapy.

The prognosis of melanoma is determined by its staging, which is based on tumor size, depth of skin invasion, lymph node involvement, and distant spread. The 5-year survival rates range from 99% for melanoma in situ (no spread) to 30% for patients with metastatic disease. This is why early diagnosis and removal is important. Regular visual inspection of the skin, preferably by a dermatologist, including areas usually sun-protected like the scalp, groin, nails, palms, and soles of the feet (yes, they look everywhere!), is important for early diagnosis and treatment. Skin lesions that are concerning for melanoma require prompt evaluation. Finally, as I have written before, never, ever use a tanning bed, as even short lengths of use are associated with melanomas. For more information go to the website of the National Cancer Institute.

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