Comorbidity burden in long-term breast cancer survivors compared with a cohort of population-based controls from the MARIE study.

Background The number of elderly cancer survivors is growing because of increasing survival rates. A high comorbidity burden in the elderly can affect their quality of life and survival. The aim of this study was to examine whether breast cancer survivors and population-based controls have a different comorbidity burden after long-term follow-up. Methods This study used data from a German breast cancer case-control study, which initially comprised 3813 breast cancer cases aged 50 to 74 years who were diagnosed between 2002 and 2005 and 7341 population-based controls. Participants were followed up in 2014/2016. A modified Charlson Comorbidity Index (mCCI) was calculated to quantify severe comorbidities. Negative binomial regression was performed to estimate rate ratios (RRs) with 95% confidence intervals (CIs) for the association between case-control status and mCCI (dependent variable) for the baseline population and for those who participated at follow-up, with adjustments made for relevant lifestyle factors. Results In total, 1925 cases and 3674 controls participated in the follow-up 12 years after recruitment. In the baseline population 35% had at least 1 comorbid condition.In long-term survivors this proportion was 52%. No difference was found in the mCCI between breast cancer cases and controls at baseline (RR, 1.05; 95% CI, 0.98-1.11) or between long-term survivors of the 2 groups at baseline (RR, 1.07; 95% CI, 0.97-1.18) or at follow-up (RR, 1.00; 95% CI, 0.91-1.10). Conclusions The comorbidity burden of long-term breast cancer survivors and controls increased over time; however, it remained similar in both groups after 12 years of follow-up.