Cardiovascular disease in males with breast cancer: a population-based cohort study

Background — There are scarce data on cardiovascular disease (CVD) risk in male breast cancer (BC).

Objectives — The objective of the study was to describe CVD risk in males with BC compared to females with BC and cancer-free males.

Methods — Population-based cohort study using linked administrative databases. We identified males diagnosed with BC in Ontario, Canada (1998-2021). Male BC patients were age-matched to 3 female BC and 3 male cancer-free controls. The primary outcome was hospitalization or emergency department visits for CVD. Cause-specific mortality was a secondary outcome. Cause-specific hazards regression was used to estimate HRs associated with male BC status.

Results — We matched 683 males with BC to 2,049 females with BC and 687 males with BC to 2,061 cancer-free males (median age 68 years [IQR: 59-77 years]). Males with BC had more prevalent pre-existing CVD and risk factors than both comparators. After adjusting for baseline characteristics, male BC was associated with a similar risk of CVD hospitalization/emergency department visits compared to female BC (HR: 1.03; 95% CI: 0.86-1.25) and cancer-free males (HR: 1.00; 95% CI: 0.84-1.19). Male BC was not associated with higher CVD mortality but was associated with higher cancer mortality relative to both comparator groups.

Conclusions — Males with BC have greater baseline cardiovascular risk than females with BC and cancer-free males but no increase in future CVD hazard after adjustment. This highlights the need for prioritizing cancer treatment in males with BC, with appropriate attention to CVD risk management.