Efficacy and safety of trastuzumab combined with chemotherapy for first-line treatment and beyond progression of HER2- overexpressing advanced breast cancer

Objective： To observe the efficacy and safety of trastuzumab combined with chemotherapy in patients with human epidermal growth factor receptor 2 （HER2）-overexpressing advanced breast cancer. Methods： A total of 90 patients with HER2-overexpressing advanced breast cancer were enrolled in this study. All patients were diagnosed with ductal invasive breast cancer by pathological analysis, and were aged between 31-73 years with a median of 51 years. HER2-positivity was defined as 3（＋） staining in immunochemistry or amplification of fluorescence in situ hybridization （FISH, ratio ≥2.0）. Trastuzumab was administered in combination with chemotherapy as first-line treatment and beyond progression as a second- line, third-line, and above treatment in 90, 34, 14, and 6 patients, respectively. The chemotherapy regimen was given according to normal clinical practice. The response rate was evaluated every two cycles, and the primary endpoints were progression-free survival （PFS） and overall survival （OS）. Survival curves were estimated by using Kaplan-Meier graphs and were compared by using log-rank test statistics. Multivariate analysis was done using Cox＇s proportional hazards regression model, and the level of significance was P〈0.05. Results： All 90 patients received at least one dose of trastuzumab, and efficacy could be evaluated in 85 patients. The median follow-up was 50 months. In total, 72 （80.00%） patients had visceral metastasis, and 43 （47.78%） patients had progressed after one or more extensive chemotherapy regimens for metastatic diseases. The median PFS for first-line trastuzumab was 10 months （range, 2-59 months）, and the median OS after metastasis or initially local advanced disease was 22 months （range, 2-1 16 months）. Conclusions： Trastuzumab combined with chemotherapy was active and well-tolerated as a first-line treatment and even beyond progression in HER2-overexpressing advanced breast cancer as a second-line or third-line treatment. However, its efficacy is certainly less beyond this point.