Global, regional, and national burden of male breast cancer in 204 countries and territories: a systematic analysis from the global burden of disease study, 1990–2021

Background: Male breast cancer (MBC) is a rare malignancy that has been under-investigated, with limited global epidemiological research dedicated to it. A comprehensive estimate of the global, regional, and national burden of MBC is valuable for policy planning. This study aims to evaluate the burden of MBC across 204 countries and territories. Methods: MBC data were collected from the 2021 Global Burden of Diseases, Injuries, and Risk Factors (GBD) Study estimates spanning from 1990 to 2021. The global incidence, prevalence, deaths, and disability-adjusted life-years (DALYs) attributed to MBC, as well as corresponding age-standardized rates, were calculated. Temporal trends, projections of incidence and mortality to 2050, lifetime risk, and risk factors of MBC were also estimated according to regions and countries. Findings: In 2021, there were 38,827 (95% uncertainty interval [UI], 24,650-47,846) new cases, 320,459 (95% UI, 220,533-384,317) prevalent cases, 13,274 (95% UI, 9074-16,240) deaths, and 380,917 (95% UI, 252,922-476,417) DALYs attributed to MBC worldwide, with the highest disease burden observed in the Eastern Sub-Saharan Africa region. From 1990 to 2021, the age-standardized incidence and mortality rates of MBC significantly increased, but they are projected to decrease over the next 30 years. High-middle Socio-demographic Index (SDI) quintile had the highest lifetime risk of developing MBC, while the low SDI quintile had the highest lifetime risk of dying from MBC. Dietary risk and alcohol use were identified as important risk factors for MBC deaths and DALYs globally. Interpretation: The global burden of MBC significantly increased from 1990 to 2021, with notable geographic disparities. Efforts aimed at MBC prevention and control strategies should take into account the inequities in its global distribution. Funding: This study was supported by the National Natural Science Foundation of China (grant numbers 82372996 and 82202913) and the Chongqing Natural Science Foundation (grant number CSTB2023NSCQ-MSX0480).