Malignant melanoma of the vulva and vagina in the United States: patterns of incidence and population-based estimates of survival.

OBJECTIVES

Our purpose was to describe the incidence of vulvar and vaginal melanoma and to evaluate risk factors. We also aimed to provide population-based estimates of survival and to evaluate prognostic factors.

STUDY DESIGN

We calculated incidence rates and survival curves based on 15 years' experience of population-based registries that together cover approximately 10% of the United States population.

RESULTS

The incidences of vulvar and vaginal melanoma were 0.108 and 0.026/10(5) per year. White women experienced an increased incidence of vulvar melanoma but not vaginal melanoma (relative risks 2.6 and 1.0 for white women, compared with black women). For vulvar melanoma the 5-year survival was 50%; regional or distant spread, older age, and black race were adverse prognostic factors. For vaginal melanoma the 5-year survival was 19%; black race was an adverse prognostic factor.

CONCLUSIONS

Vulvar melanoma and vaginal melanoma differ from nongenital cutaneous melanoma in epidemiologic features, which is consistent with the hypothesized systemic sun-induced melanoma-inhibitory factor and with melanin interference with nonultraviolet carcionogenesis. These population-based data identified prognostic factors and confirmed the poor prognosis of these tumors.