Delayed initiation of adjuvant chemotherapy in older women with breast cancer

BACKGROUND: Adjuvant chemotherapy benefits early‐stage breast cancer (BC) patients. Older women receive guideline‐adherent treatment less frequently and experience treatment delays more frequently. We evaluated factors associated with delaying adjuvant chemotherapy and the delays’ survival impact in a large population–based cohort of elderly BC patients. METHODS: Patients age >66 years diagnosed 2001‐2015 with localized or regional BC were identified in the SEER‐Medicare and Texas Cancer Registry‐Medicare databases. Time from surgery to chemotherapy (TTC) was categorized into four groups: 0‐30, 31‐60, 61‐90, and >90 days. We identified predictors of delays, estimated overall (OS) and BC‐specific (BCSS) survival, and determined the association between TTC and outcome adjusting for other variables. RESULTS: Among 28,968 women (median age 71 years), median TTC was 43 days. 10.7% of patients experienced TTC >90 days. Older age, Black or Hispanic race/ethnicity, unmarried status, more comorbidities, hormone receptor‐positivity, mastectomy, Oncotype DX testing, and full state buy‐in were associated with increased risk of delay. Five‐year OS estimates by TTC group were 0.82, 0.81, 0.80, and 0.74, respectively (p<.001). BCSS demonstrated a similar trend (p<.001). Chemotherapy delay was associated with worse OS (HR=1.33, 95%CI 1.25‐1.40) and BCSS (HR=1.39, 95%CI 1.27‐1.53). In subgroup analysis, delayed chemotherapy was associated with worse OS and BCSS among patients with hormone receptor–positive (HR=1.56, 95%CI 0.97‐2.51), HER2‐positive (HR=1.99, 95%CI 1.04‐3.79), and triple‐negative (HR=2.15, 95%CI 1.38‐3.36) tumors. CONCLUSION: Chemotherapy delays are associated with worse survival in older BC patients. Providers should avoid delays and initiate chemotherapy ≤90 days after surgery regardless of patients’ BC subtype or age.