Poorer survival outcomes for male breast cancer compared with female breast cancer may be attributable to in-stage migration.

Background: Male breast cancer accounts for less than 1% of all breast cancers, yet males have a worse prognosis than females with breast cancer.

Methods: Using the 1988-2003 Surveillance, Epidemiology, and End Results Program data, we conducted a retrospective, population-based cohort study to investigate stage-specific differences in breast cancer-specific and all-cause mortality between males and females. We calculated adjusted hazard ratios (aHR) and 95% confidence intervals (CI) using Cox regression models to compare breast cancer-specific and all-cause mortality by stage between males and females, controlling for potential confounding variables.