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.