Histologic features of tumors and the female superiority in survival from malignant melanoma.

The primary tumors of 780 patients with clinical Stage I malignant melanoma were reviewed to seek reasons for the female superiority in survival. Histologic features of tumors believed to be of prognostic significance were examined: tumor thickness, evidence of regression, histogenetic type, and mitotic activity. The average tumor thickness was significantly less in women, due to a preponderance of very thin lesions in women and very thick lesions in men. In both men and women, there proved to be a direct correlation between five-year survival rate and tumor thickness, but women had a higher survival rate than men at each thickness level. These latter two findings, in combination, could contribute to the overall female superiority in survival. No further insight into the sex difference in survival was obtained from the examination of the other histologic features. Although the incidence of partial lesion regression was not markedly different except for very thin lesions. There were no disparities between the sexes in the incidences of histogenetic types or grades of mitotic activity, two histologic features which drew their prognostic significance only from their correlation with tumor thickness.