RESUMO
BACKGROUND: Previous large trials with trastuzumab (TZM) showed improved outcome in patients with HER2-positive early-stage breast cancer. However, the efficacy and safety of TZM in Japanese patients have not been fully evaluated. We have therefore conducted an observational study in Japan. METHODS: This was a retrospective and a prospective observational study in which data on women with histologically confirmed HER2-positive invasive breast cancer who received TZM for stage I-IIIC disease were collected from 56 institutions that participated in the Japan Breast Cancer Research Group and the efficacy of each treatment regimen analyzed. RESULTS: A total of 2,024 patients treated between July 2009 and June 2011 were initially enrolled in this study; in August 2013, the patient cohort comprised 2,009 patients. Of these, 142 (7.5 %) were aged ≥70 years, 1,097 (58.1 %) had clinically node-negative (cN0) breast cancer, and 883 (47.4 %) were estrogen receptor-positive. Treatment options were neoadjuvant therapy (662 patients) and adjuvant therapy with TZM (1,228 patients). Three-year overall survival (OS) rates in the entire cohort and in the neoadjuvant and adjuvant cohorts, respectively, were 98.9 [95 % confidence interval (CI) 98.2-99.3], 98.3 (95 % CI 96.8-99.1 %), and 99.2 % (95 % CI 98.4-99.6), respectively. Three-year disease-free survival (DFS) rates in the entire cohort and in the neoadjuvant and adjuvant cohorts, respectively were 94.2 (95 % CI 93.0-95.2), 94.8 (95 % CI 93.0-95.9), and 93.1 (95 % CI 90.7-94.9 %), respectively. Multivariate analysis showed that age and nodal status negatively correlated with DFS. Age was the only factor which correlated with OS rate. Adverse events (AEs) associated with TZM and grade 3/4 AEs were reported in 356 (18.8 %) and 14 (0.6 %) patients, respectively. Grade 3/4 cardiac toxicities were reported in 11 patients. CONCLUSION: Based on data from our patient cohort of Japanese women with HER2-positive early-stage breast cancer, the efficacy and safety of systemic therapy with TZM are comparable to data from previously conducted large trials. Progress in anti-HER2 therapy for patients aged ≥70 years who have a poorer prognosis is needed.
