Frailty and long-term mortality of older breast cancer patients: CALGB 369901 (Alliance).

Purpose: Breast cancer patients aged 65+ ("older") vary in frailty status. We tested whether a deficits accumulation frailty index predicted long-term mortality.

Methods: Older patients (n = 1280) with non-metastatic, invasive breast cancer were recruited from 78 Alliance sites from 2004 to 2011, with follow-up to 2015. Frailty categories (robust, pre-frail, and frail) were based on 35 baseline illness and function items. Cox proportional hazards and competing risk models were used to calculate all-cause and breast cancer-specific mortality for up to 7 years, respectively. Potential covariates included demographic, psychosocial, and clinical factors, diagnosis year, and care setting.

Results: Patients were 65-91 years old. Most (76.6%) were robust; 18.3% were pre-frail, and 5.1% frail. Robust patients tended to receive more chemotherapy ± hormonal therapy (vs. hormonal) than pre-frail or frail patients (45% vs. 37 and 36%, p = 0.06), and had the highest adherence to hormonal therapy. The adjusted hazard ratios for all-cause mortality (n = 209 deaths) were 1.7 (95% CI 1.2-2.4) and 2.4 (95% CI 1.5-4.0) for pre-frail and frail versus robust women, respectively, with an absolute mortality difference of 23.5%. The adjusted hazard of breast cancer death (n-99) was 3.1 (95% CI 1.6-5.8) times higher for frail versus robust patients (absolute difference of 14%). Treatment differences did not account for the relationships between frailty and mortality.

Conclusions: Most older breast cancer patients are robust and could consider chemotherapy where otherwise indicated. Patients who are frail or pre-frail have elevated long-term all-cause and breast cancer mortality. Frailty indices could be useful for treatment decision-making and care planning with older patients.