MELANOMAS are malignant tumours derived from melanocytes. The most common site of involvement is the skin, although occasionally primary melanoma develops in other organs (eye, oral and nasal mucosa, vulval and anorectal mucosa, other gastrointestinal mucosa and CNS).
Melanomas are a major cause of premature death from cancer.
Recognised risk factors include personal or family history of melanoma, large numbers of naevi and/or dysplastic naevi, giant congenital melanocytic naevi, fair complexion, a tendency to sunburn, solar-damaged skin, a history of nonmelanoma skin cancer, and immunodeficiency.
The most common sites for melanoma are the legs of women and the backs of men, despite these not being the sites of greatest sun exposure. Early detection is associated with improved survival.
Any malignancy will grow, grow irregularly, and function abnormally. A melanoma produces pigment in abnormal amounts and elicits an immune response that will be reflected in the clinical appearance. A small but significant number of melanomas are undiagnosable clinically. A history of change may be the only clue to the correct diagnosis (tables 1 and 2, see next page).
In 2008, the incidence of melanoma in Australia was 11,442 and 1224 people died from melanoma. Survival at five years following newly diagnosed invasive melanoma (Clark’s level 2-5) has increased from 85% in 1986 to 90% in 2010.
In the absence of any new significant chemotherapy in that period, this improvement has been attributed to public education, early diagnosis and excision.
Scar re-excision, sentinel node biopsy, elective lymph node dissection, chemotherapy, radiotherapy and immunotherapy may improve survival at one year but have not been shown to improve five-year survival. Adjuvant therapy with interferon may improve five-year survival by 10% but is associated with significant toxicity.
Macroscopic locoregional lymph node metastasis reduces five-year survival to 50%. Distant visceral or bone metastasis (stage IV disease) has a one-year survival of about 25% and a five-year survival of less than 2.5%. Following successful surgical resection of metastasis, the median disease-free time to relapse is six weeks.
Click here to read more in the article published on 3 May 2013 by Professor Rodney Sinclair.