Toxicity risk score and clinical decline after adjuvant chemotherapy in older breast cancer survivors

Chemotoxicity risk scores were developed to predict grade 3-5 chemotherapy toxicity in older women with early breast cancer. However, whether these toxicity risk scores are associated with clinically meaningful decline in patient health remains unknown.In a prospective study of women ≥65 with stage I-III breast cancer treated with chemotherapy, we assessed chemotoxicity risk using the Cancer and Aging Research Group-Breast Cancer (CARG-BC) score (categorized as low, intermediate, high). We measured patient health status before (T1) and after (T2) chemotherapy using a clinical frailty index (Deficit Accumulation Index [DAI; categorized as robust, prefrail, frail]). The population of interest was robust women at T1. The primary outcome was decline in health status after chemotherapy, defined as a decline in DAI from robust at T1 to pre-frail or frail at T2. Multivariable logistic regression was used to examine the association between T1 CARG-BC score and decline in health status, adjusted for sociodemographic and clinical characteristics.Of the 348 robust women at T1, 83 (24%) experienced declining health status after chemotherapy, of whom 63% had intermediate/high CARG-BC scores. After adjusting for sociodemographic and clinical characteristics, women with intermediate (OR = 3.14, 95% CI 1.60-6.14, p < 0.001) or high (OR = 3.80, 95% CI 1.35-10.67, p = 0.01) CARG-BC scores had greater odds of decline in health status compared to women with low scores.In this cohort of older women with early breast cancer, higher CARG-BC scores prior to chemotherapy were associated with decline in health status after chemotherapy independent of sociodemographic and clinical risk factors.