Survival Outcomes of Retreatment with Trastuzumab and Cytotoxic Chemotherapy for HER2-Positive Recurrent Patients With Breast Cancer Who Had Been Treated with Neo/adjuvant Trastuzumab Plus Multidrug Chemotherapy: A Japanese Multicenter Observational Study

Background:There are little data on the usefulness of trastuzumab (TZM) retreatment as the first-line treatment for patients with HER2 (human epidermal growth factor receptor 2)–positive breast cancer recurrence after perioperative treatment with TZM.Aim:To clarify the outcome and safety of TZM retreatment in patients with recurrent HER2-positive breast cancer.Method:An observational study was conducted on patients who relapsed after primary systemic therapy with TZM using the central registration system. The primary end point was progression-free survival (PFS). Secondary end points consisted of the response rate, overall survival (OS), and safety.Result:In total, 34 patients were registered between July 2009 and June 2012. The median follow-up time was 23.7 months (2-24 months). The 1- and 2-year PFS rates were 46.9% (95% confidence interval (95% CI): 29.2%-62.9%) and 29.8% (95% CI: 15.0%-46.3%), respectively (median 10.6 months). The median PFS time for patients receiving TZM combined with CTx was 13.9...