Sex differences in presentation of cutaneous malignant melanoma and in survival from stage I disease.

To explain the improved survival rates of females with malignant melanoma compared with that of males in this region of the United Kingdom (a recognized low incidence area for melanoma), clinicopathologic differences between the sexes of 477 patients presenting with primary melanoma at all stages, were examined between 1961 and 1976. The survival of 356 males and females presenting with Stage I melanoma were also compared, taking death from melanoma as the critical event. The data were analyzed using the Cox multivariate model, which allows several prognostic variables to be considered simultaneously, and enabled the assessment of the effect of, and interactions between, these variables. Female superiority in survival was due to: more lesions on the female lower limb, a site associated with a good prognosis; thinner lesions at presentation in the female; an interaction with age in which females between the age of 50 and 79 years fare significantly better than a similar age group of males. This age/sex interaction has not been observed in high incidence areas. It suggests, therefore, that melanoma may behave differently in different geographical areas.