Racial and ethnic disparities and socioeconomic determinants of male breast cancer mortality in the United States.

PURPOSE: Male breast cancer (mBC) is rare and accounts for ~ 1% of all breast cancer cases in the United States (US), and mBC incidence has risen in recent years. This study sought to examine mBC mortality disparities across racial/ethnic groups and associated socioeconomic determinants at the national level. METHODS: This retrospective study analyzed the 2010-2021 National Cancer Database. Patients were eligible if they were ≥ 18 years, were male sex, and had stage I-IV disease, with available data on receptor status. Overall survival (OS) was modeled using Cox regression adjusting for demographic, socioeconomic, and clinicopathologic factors. RESULTS: Of 20,470 mBC (mean age, 66.2 [SD, 12.6] years), 2.5% were Asian or Pacific Islander, 13.8% Black, 4.0% Hispanic, and 78.2% White. After controlling for clinicopathologic characteristics, Black patients had worse OS than White patients (adjusted hazard ratio [AHR], 1.22; 95% CI, 1.12-1.32); however, when further adjusting for socioeconomic factors, this difference was no longer significant (AHR, 1.09; 95% CI, 0.99-1.21). Hispanic patients (AHR, 0.76; 95% CI, 0.62-0.94) had a lower mortality risk. OS varied across tumor stages and molecular subtypes. In the triple-negative mBC cohort, Asian or Pacific Islander patients had worse OS than White patients (AHR, 2.35; 95% CI, 1.21-4.55), warranting further investigation. Additionally, lower median household income, lack of health insurance, Medicaid/Medicare, and comorbidities were associated with a higher mortality risk. CONCLUSION: Our findings highlight elevated mortality risks of mBC among Black patients, among Asian or Pacific Islander patients with TNBC, and associations with household income and insurance status. Interventions addressing socioeconomic inequities that impact access to cancer care programs and services may help reduce racial/ethnic disparities and improve mBC survival outcomes.