Worsening frailty and declining quality of life in older survivors of non-metastatic breast cancer.

Breast cancer treatment can worsen frailty, but the impact of this decline on long-term quality of life (QoL) remains uncertain. We identified women ≥65 years old with non-metastatic breast cancer from the Life and Longevity after Cancer survivorship cohort of the Women's Health Initiative. We examined the association between clinically-significant worsening of frailty, measured by a validated claims-based index one year post-diagnosis, and long-term decline in QoL, assessed on a ten-point scale 4 to 6 years post-diagnosis. Among 1,061 eligible patients, 692 (65.2%) were robust (not living with frailty), 343 (32.3%) were living with pre-frailty, and 26 (2.5%) were living with frailty at cancer diagnosis. Clinically-significant worsening of frailty occurred in 19.5% of patients. In fully adjusted models, worsening frailty was significantly associated with long-term QoL declines (Odds Ratio 1.48; 95% Confidence Interval [1.07 to 2.04]). These findings highlight the need for interventions to prevent worsening frailty during breast cancer treatment.