Impact of Baseline Cardiovascular Comorbidity on Outcomes in Women With Breast Cancer: A Real-world, Population-based Study

Introduction: The aim of this study was to characterize treatment trends and outcomes of women who have preexisting cardiovascular disease (CVD) prior to the diagnosis of breast cancer.

Patients and methods: This represented a retrospective, population-based cohort study that analyzed pooled data from the provincial cancer registry, physician billing claims, hospital discharge abstracts, ambulatory care, and the 2011 census in a large Canadian province. Multivariable logistic regression was performed to identify the associations of CVD with breast cancer treatment and outcomes. Kaplan-Meier analyses were conducted and survival was compared between CVD and non-CVD groups. Cox regression models were constructed to determine the effect of CVD on overall and cancer-specific survival.

Results: A total of 25,594 women with breast cancer were eligible and included in the current analysis. Preexisting CVD was associated with a lower likelihood of receiving chemotherapy (odds ratio [OR], 0.56; 95% confidence interval [CI], 0.48-0.66; P < .0001) and radiotherapy (OR, 0.75; 95% CI, 0.67-0.83; P < .0001), but a higher probability of undergoing mastectomy (OR, 1.13; 95% CI, 1.03-1.25; P = .011). Unadjusted Kaplan-Meier analyses showed that individuals with preexisting CVD experienced worse median overall and cancer-specific survival when compared with those without CVD (87 vs. 150 months and 106 vs. 131 months, respectively; both P < .0001). Adjusting for measured confounders, the presence of preexisting CVD continued to predict for worse overall survival (hazard ratio, 1.55; 95% CI, 1.43-1.67; P < .0001), but not cancer-specific survival (hazard ratio, 1.11; 95% CI, 0.98-1.27; P = .099).

Conclusions: Patients with breast cancer with preexisting CVD are less likely to receive recommended treatment for their cancer and more likely to exhibit worse overall survival.