Gender Disparity and Mutation Burden in Metastatic Melanoma

Gender differences in melanoma incidence and outcome have been consistently observed but remain biologically unexplained. We hypothesized that tumors are genetically distinct between men and women and analyzed the mutation spectra in 266 metastatic melanomas (102 women and 164 men) from The Cancer Genome Atlas (TCGA). We found a statistically significantly greater burden of missense mutations among men (male median 298 vs female median = 211.5; male-to-female ratio [M:F] = 1.85, 95% confidence interval [CI] = 1.44 to 2.39). We validated these initial findings using available data from a separate melanoma exome cohort (n = 95) and found a similar increase in missense mutations among men (male median 393 vs female median 259; M:F = 1.59, 95% CI = 1.12 to 2.27). In addition, we found improved survival with increasing log-transformed missense mutation count (univariate hazard ratio = 0.82, 95% CI = 0.69 to 0.98) for TCGA samples. Our analyses demonstrate for the first time a gender difference in mutation burden in cutaneous melanoma.