De Novo metastatic breast cancer in males versus females: a Swedish, population-based cohort study.

Current evidence on de novo metastatic breast cancer (dnMBC) is based on data from women. This Swedish, population-based cohort study compared the incidence over time and prognosis of dnMBC between sexes using data from the National Quality register for Breast Cancer. Joinpoint regression analysis was used to compare incidence trends in all stages (104,733 women, 648 men) and multivariate Cox regression analysis to investigate potential sex disparities in dnMBC prognosis (6005 women, 41 men). For both sexes, increased trends were evident for stages I-II with a stabilizing trend at the later years for women while stage III incidence remained stable. An increased trend for dnMBC in women, and to less extent in men, was observed. No difference in dnMBC overall survival between sexes was observed (HR : 1.24; 95% CI : 0.85-1.81). The comparable features in terms of incidence and prognosis of dnMBC between sexes imply similarities supporting the adoption of common treatment strategies.