Impact of timing of trastuzumab initiation on long-term outcome of patients with early-stage HER2-positive breast cancer: the “one thousand HER2 patients” project

BACKGROUND: The optimal timing of (neo)adjuvant trastuzumab initiation with respect to chemotherapy and surgery remains undefined. METHODS: Retrospective analysis of a large institutional database of HER2-positive patients who received anti-HER2 therapy. We included all Stage I to III patients treated with trastuzumab with a minimum follow up of 3 years. The date of first breast biopsy was recorded as initial diagnosis. RESULTS: A total of 506 patients [adjuvant: 386 (76%)-neo-adjuvant: 120 (24%)] were included. The median time-to-first-trastuzumab (TFT) from diagnosis was 12 weeks (range 1.9–122.3). Median follow-up is 73.3 months (range 1.4–176.3). TFT was significantly shorter in the neo-adjuvant than in the adjuvant cohort (median: 4.4 vs. 14 weeks, p < 0.00001). Despite the neo-adjuvant cohort having significantly more node-positive patients (75 vs. 53%, p < 0.0001), DFS rate (neo-adjuvant: 12.5 vs. adjuvant: 18%, p = 0.094) was numerically superior in neo-adjuvant patients. A TFT ≤ 12 weeks was associated with significantly superior DFS and OS over TFT > 12 weeks. Early concomitant regimens were associated with superior DFS over delayed-concomitant and sequential regimens. CONCLUSIONS: Initiating trastuzumab more than 12 weeks from diagnosis has a negative impact on clinical outcome. Neo-adjuvant anti-HER2 therapy could be the optimal strategy to treat early stage HER2-positive breast cancer.