Cardiovascular and Other Competing Causes of Death in Male Breast Cancer Patients: A Population-Based Epidemiologic Study

Abstract

Purpose

Male breast cancer (MBC) is a rare disease that tends to occur in elderly men. Little is known about the causes of death in MBC because of the small sample size of most studies. This study aimed to investigate the causes of death in MBC patients.

Patients and Methods

MBC patient data were obtained from the Surveillance, Epidemiology, and End Results database (1975–2016). Time trends of MBC mortality in the US population were analyzed using Joinpoint software. We calculated the proportion of each cause of death in the overall cohort and in different patient subgroups. Competing risk models were used to calculate cumulative mortality at different follow-up times. The risk of cardiovascular death (CVD) in MBC patients was compared to that of the age-matched general population by calculating standardized mortality ratio (SMR).

Results

In total, 6426 patients were included in the analysis. MBC mortality rate increased between 2004 and 2019 (annual percentage change=1.16, 95% confidence interval [CI]: 0.50, 1.80). There were 1757 patients (27.3%) who died of non-breast cancer causes. CVD was the leading cause of death in patients who were elderly or had localized disease. MBC patients had a 6.58-fold higher risk of CVD than the general population (SMR=6.58, 95% CI: 6.14, 7.05).

Conclusion

Non-breast cancer death accounts for the majority of deaths in MBC patients who are elderly or have localized cancer. Compared to the general population, MBC patients have an increased risk of CVD. These results highlight the importance of monitoring cardiovascular comorbidities in MBC patients.

Keywords:

• male breast cancer
• cardio-oncology
• elderly patients
• cause of death
• non cancer death
• cardiovascular death

Acknowledgments

We thank all the staffs from the SEER and CDC WONDER for providing the research data.

Abbreviations

APC, annual percentage change; ASCO, American Society of Clinical Oncology; CDC, Centers for Disease Control and Prevention; CI, confidence interval; CVD, cardiovascular death; FBC, female breast cancer; MBC, male breast cancer; SEER, Surveillance, Epidemiology, and End Results; SMR, standardized mortality ratio; WONDER, Wide-ranging Online Data for Epidemiologic Research.

Data Sharing Statement

The datasets analyzed in the current study are publicly available from the SEER database (http://seer.cancer.gov).

Statement of Ethics

Ethics approval was not required because the analyzed data are publicly available.

Disclosure

The authors have no conflicts of interest to declare.