The impact of cardiovascular disease on all-cause and cancer mortality: results from a 16-year follow-up of a German breast cancer case–control study

Abstract

Abstract Background Cardiovascular disease (CVD) is the leading cause of death worldwide. The aim of this study was to examine if CVD affects the mortality of women after a breast cancer diagnosis and population controls differently. Methods The analysis included a total of 3,555 women, diagnosed with primary stage 1–3 breast cancer or in situ carcinoma between 2002 and 2005 and 7,334 controls breast cancer-free at recruitment, all aged 50–74 years, who were followed-up in a German breast cancer case–control study until June, 30 2020. Kaplan–Meier and cumulative incidence function were calculated for all-cause mortality and mortality from any cancer, stratified for case–control status and CVD, separately for women aged < 65 and ≥ 65 years. Cox regression and Fine-Gray subdistribution hazard models were used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI) for the association between case–control-status, CVD and mortality from all causes/any cancer. Results The median follow-up was 16.1 years. In total, 1,172 cases (33.0%) and 1,401 initial controls (19.1%) died. CVD prevalence at recruitment was 15.2% in cases and controls. Cases with CVD had the highest and controls without CVD the lowest mortality during the entire observation period in both age groups (< 65 and ≥ 65 years). CVD was identified as a risk factor for all-cause mortality in both cases and controls aged < 65 years (HR 1.22, 95%CI 0.96–1.55 and HR 1.79, 95%CI 1.43–2.24) as well as at ages of ≥ 65 years (HR 1.44, 95%CI 1.20–1.73 and HR 1.59, 95%CI 1.37–1.83). A significant association of CVD and cancer mortality was found only for cases aged ≥ 65 years. Conclusion CVD was significantly associated with all-cause mortality of both cases and controls and CVD was identified as a risk factor for cancer mortality of cases aged ≥ 65 years at recruitment. Therefore, attention should be paid on monitoring and preventing CVD in breast cancer patients, especially in those diagnosed at older ages.