Pathological complete response and prognosis after neoadjuvant chemotherapy for HER2-positive breast cancers before and after trastuzumab era: results from a real-life cohort

Background: Trastuzumab was introduced a decade ago and has improved outcomes for HER2-positive breast cancer. We investigated the factors predictive of pathological complete response (pCR), prognostic factors for disease-free survival (DFS), and interactions between pCR and DFS after neoadjuvant treatment. Methods: We identified 287 patients with primary HER2-positive breast cancers given neoadjuvant chemotherapy (NAC) between 2002 and 2011. Univariate and multivariate analyses of clinical and pathological factors associated with pCR and DFS were performed. Results: pCR rates differed between patients receiving neoadjuvant trastuzumab treatment or not (47.7% versus 19.3%, P