Survival superiority of females with melanoma. A multivariate analysis of 6383 patients exploring the significance of gender in prognostic outcome

Abstract

Objective: To evaluate the effects of gender on prognostic outcome of patients with melanoma.

Design: Retrospective cohort study, including 20 years of follow-up.

Setting: Duke University Melanoma Clinic, Durham, NC, a referral center for patients with melanoma.

Patients: Patients with melanoma (N = 6383), consisting of 45% females and 55% males, obtained from a referred sample. Eligibility requirements were nonocular melanomas and white race.

Main outcome measures: Time to metastases and survival.

Results: Females with melanoma demonstrated a superior prognostic outcome over males, with a 34% survival advantage and a 28% disease-free advantage. When each of the variables of age, site, Clark's level, histologic type, and tumor thickness was explored for possible influences on prognostic outcome, female survival advantage persisted, although modified by independent variables. The greatest influence came from the variables of site, Clark's level, and Breslow's thickness. Age, specifically in premenopausal vs postmenopausal age groups, was not significant in altering females' prognostic advantage. A multivariate analysis combining the effects of all the variables resulted in females still maintaining a 22% survival advantage and a 17% disease-free advantage.

Conclusions: Females with melanoma have a significant prognostic advantage over their male counterparts that cannot be fully explained by influences from the variables of age, site, Clark's level, histology, and Breslow's thickness. This superior prognostic outcome does not appear to be associated with menstrual status. Evidence does suggest that the protective factor for females occurs at the level of metastases.