Shorter duration of first-line chemotherapy reflects poorer outcomes in patients with HER2-negative advanced breast cancer: a multicenter retrospective study

Post-progression survival affects overall survival (OS) in patients with HER2-negative advanced breast cancer (HER2-ABC); thus, the optimal choice of first-line chemotherapy (1LCT) remains controversial. We investigated patients with HER2-ABC focusing on their sensitivity to 1LCT. We retrospectively analyzed patients with HER2-ABC who received 1LCT between January 2011 and December 2016 in three participating institutions. We identified 149 patients in the shorter and 152 patients in the longer time to treatment failure (TTF) groups. The median OS was significantly longer in the longer TTF group (hazard ratio [HR] 0.44, P < 0.001, log-rank). In the shorter TTF group, OS of patients who received paclitaxel plus bevacizumab (PB) therapy was significantly inferior to that of those who received chemotherapy other than PB (HR 2.57, P < 0.001, log-rank), and subsequent eribulin therapy significantly improved OS from 1LCT initiation (Wilcoxon P < 0.001); multivariate analyses showed that 1LCT PB therapy was an independent risk factor for poorer OS (HR 2.05, P = 0.003), while subsequent eribulin therapy was an independent prognostic factor for better OS (HR 0.56, P = 0.004). OS was significantly poorer in patients with HER2-ABC with a shorter duration of 1LCT, including PB therapy, while subsequent eribulin therapy improved OS.