Adjuvant capecitabine in patients with triple-negative breast cancer after neoadjuvant chemotherapy

For patients diagnosed with triple-negative breast cancer (TNBC), residual disease (RD) after neoadjuvant chemotherapy (NAC) is associated with increased rates of recurrence and poor prognosis. Adjuvant therapy with capecitabine is considered standard management for TNBC-RD based on the CREATE-X study, although real-world data are limited. Real-world utilization of adjuvant capecitabine for patients with TNBC-RD and the association of capecitabine with survival outcomes remains largely unknown.

We evaluated survival outcomes in patients with stage I-III TNBC (including estrogen and progesterone receptor <10%) who received NAC and underwent breast surgery between January 2016 and June 2019 at three comprehensive cancer centers. Treatment in the adjuvant setting was categorized as capecitabine, other systemic therapy, or no adjuvant therapy. Propensity score methods were used to control potential confounding effects from baseline covariates. Survival outcomes were estimated using Kaplan-Meier and propensity weighted Cox proportional hazards models.

In the total population, 661/977 (67.7%) had RD after NAC; the NAC regimens were primarily anthracycline-taxane (n = 611; 62.5%), anthracycline-taxane-platinum (n = 180; 18.4%), or taxane-platinum (n = 39; 4.0%). Among patients with TNBC-RD, 45.1% (298/661) did not receive any adjuvant therapy. Among those who received adjuvant therapy, 202/363 (55.6%) received capecitabine, 115/363 (31.7%) other chemotherapy, and 46/363 (12.7%) endocrine or targeted therapy. At a median follow-up of 3.5 years, receipt of capecitabine was associated with significantly improved recurrence-free survival [RFS; propensity-adjusted hazard ratio (HR) 0.70, 95% confidence interval (CI) 0.54-0.91, P = 0.008], distant recurrence-free survival (DRFS; HR 0.71, 95% CI 0.54-0.93, P = 0.01), and overall survival (OS; HR 0.66, 95% CI 0.49-0.90, P = 0.009).

In this large cohort of patients with TNBC-RD after NAC, omission of adjuvant therapy was common, with less than one-third of patients receiving adjuvant capecitabine. Receipt of adjuvant capecitabine was associated with significantly improved RFS, DRFS, and OS.