Malignant melanoma of the vulva treated by radical hemivulvectomy. A prospective study of the gynecologic oncology group

Abstract

Background. Beginning in 1983, the Gynecologic Oncology Group (GOG) conducted a prospective clinicopathologic study of primary malignant melanoma of the vulva. The objectives of this study were to determine the relationship of histopathologic parameters and microstaging to the International Federation of Gynaecology and Obstetrics (FIGO) staging and prognosis. Methods. All patients with primary untreated malignant melanoma of the vulva and no history of previous or subsequent other primary invasive malignancy were eligible for study entry. All patients were required to have modified radical hemivulvectomy as minimal therapy. Groin dissection was optional. Histopathologic specimens were reviewed for capillary space involvement, Clark's level, Breslow's depth of invasion, cell type, and melanin distribution. Patient characteristics were analyzed in their relationship to groin node status and recurrence-free interval. Results. Between 1983 and 1990, 81 patients were entered in the study. Of these, 71 were evaluable. Thirty-four patients underwent radical hemivulvectomy, and 37 patients underwent radical vulvectomy. In addition, 56 patients underwent groin node dissection. The factors that were independently correlated with groin node status were: capillary lymphatic space involvement (P = 0.0001) and central primary tumor location (i.e., bilateral/clitoral/T3) (P = 0.003). The other factors that were significant—clinical tumor size, vulvar staging (FIGO), GOG performance status, and Breslow's depth of invasion—were not independent predictors of positive nodes. The factor with the highest significant correlation with recurrence-free interval was the 1992 staging system of the American Joint Committee on Cancer (AJCC) for malignant melanoma of the skin. Using multiple regression, AJCC stage was the only independent prognostic factor. In the absence of AJCC stage, Breslow's depth of invasion was the most prognostic. Conclusions. The biologic behavior of vulvar melanoma is similar to other nongenital cutaneous malignant melanoma.