Male breast cancer (MBC) is rare and comprises < 1% of breast cancers. The incidence of MBC has increased by 40% from 1975 to 2015. It is projected that 2800 new cases of invasive MBCs will be discovered in the US in 2023, and 530 men will die from it. We examined the demographics of MBC and assessed the racial differences influencing survival.
We performed a retrospective cohort study of the Surveillance, Epidemiology, and End Results (SEER) database for patients diagnosed with primary MBC between 2000 and 2019 in the United States. Patient demographics, tumor characteristics, and treatments were analyzed by descriptive statistics. Cox proportional hazards regression analysis was performed to identify the factors influencing survival, followed by subgroup analysis by Caucasian (WH) and African American (AA) race.
A total of 8373 patients had MBC. AA had 1111 (13.26%) and WH had 6817 (81.41%) MBC cases. AA had a median age of diagnoses of 69 vs WH of 63 years. AA (22.4%) men with MBC had a higher mortality rate (HR 1.44) than WH (16.8%). Older patients were found to be at increased risk of mortality in AA (HR 1.07) and WH (HR 1.17). Tumor size <20 mm halved the risk of death in WH (HR 0.56), it did not have any significance in AA. Regional lymph node involvement increased the risk of death in AA and WH (HR 4.79 vs 4.05). Poorly differentiated tumors had worse outcomes in WH than AA (HR 2.11 vs. 1.8). ER/PR + status was protective for both races. Mortality was higher in AA men residing in rural areas (HR 1.47) and lower for AA men in urban cities. Marriage improved outcomes for both AA (HR 0.63) and WH (HR 0.61). Surgery alone had better outcomes, AA (HR 0.21) and WH (HR 0.14) than chemotherapy or radiation. Median income was of no significance on survival in either race.
Overall, there is a significant difference in incidence and factors influencing survival for male breast cancer between Caucasians and African Americans. Despite the markedly lower incidence of MBC in the AA population, they have poorer outcomes overall. Further studies are required to determine the specific reasons for the disparity in their survival.
The authors.
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All authors have declared no conflicts of interest.