Comorbidities and the risk of cardiovascular disease mortality among racially diverse patients with breast cancer

BACKGROUND Women who have coexisting comorbidities at the time of breast cancer diagnosis have an increased risk of breast cancer and overall mortality. However, the associations between newly diagnosed comorbidities and the risk of cardiovascular disease (CVD) mortality among these patients have not been examined. METHODS The authors compared the associations between coexisting and newly diagnosed CVD, type 2 diabetes, and hypertension and the risk of CVD mortality among patients with breast cancer identified in the Missouri Cancer Registry. In total, 33,099 women who had incident invasive breast cancer with inpatient and outpatient hospital discharge data within 2 years after breast cancer diagnosis were included: 9.3% were Black. Subdistribution hazard ratios (sdHRs) and 95% CIs were calculated for the risk of CVD-related mortality using adjusted Cox proportional hazards regression models, accounting for a competing risk of breast cancer deaths. RESULTS Within the first 2 years after breast cancer, the most reported newly diagnosed comorbidity was hypertension (9%), followed by CVD (4%), and type 2 diabetes (2%). CVD mortality was increased in women who had newly diagnosed CVD (sdHR, 2.49; 95% CI, 2.09-2.99), diabetes (sdHR, 2.16; 95% CI, 1.68-2.77), or hypertension (sdHR, 2.06; 95% CI, 1.71-2.48) compared with women who did not have these conditions. Associations were similar by race. The strongest association was among women who received chemotherapy and then developed CVD (sdHR, 3.82; 95% CI, 2.69-5.43). CONCLUSIONS Monitoring for diabetes, hypertension, and CVD from the time of breast diagnosis may reduce CVD mortality.