Frailty among breast cancer survivors: Evidence from Swedish population data.

Breast cancer is the most common cancer among women, and incidence and survival have been increasing, leaving survivors at risk of aging-related health conditions. In this matched cohort study, we examined frailty risk with the Hospital Frailty Risk Score among breast cancer survivors (n=34900) and age-matched comparison subjects (n=290063). Women born 1935-1975 registered in the Swedish Total Population Register 1/1/1991-12/31/2015 were eligible for inclusion. Survivors had a first breast cancer diagnosis 1991-2005 and survived ≥5 years after initial diagnosis. Death date was determined by linkage to the National Cause of Death Registry until 12/31/2015. In subdistribution hazard models, cancer survivorship was weakly associated with frailty (SHR=1.04, 95% CI 1.00, 1.07). In age-stratified models, those diagnosed at younger ages (<50) had higher risk of frailty (SHR=1.12, 95% CI 1.00, 1.24) than those diagnosed at 50-65 (SHR=1.03, 95% CI 0.98, 1.07) or >65 (SHR=1.09, 95% CI 1.02, 1.17) years. Additionally, there was increased risk of frailty post-2000 (SHR=1.15, 95% CI 1.09, 1.21) compared to pre-2000 (SHR=0.97, 95% CI 0.93, 1.17). This supports work from smaller samples showing that breast cancer survivors have increased frailty risk, particularly when diagnosed at younger ages. Future work further exploring these associations and developing interventions is needed.