Trastuzumab plus adjuvant chemotherapy for human epidermal growth factor receptor 2 (HER2)-positive early-stage breast cancer: A real-world retrospective study in Chinese patients

OBJECTIVE: To assess the long-term effectiveness and safety of trastuzumab in adjuvant therapy for Chinese patients with early-stage human epidermal growth factor 2 (HER2)-positive breast cancer in a real-world setting. METHODS: This retrospective observational study analyzed the medical records of HER2-positive breast cancer patients between 2000 and 2012 at the Chinese Academy of Medical Sciences. Patients who received adjuvant chemotherapy alone or adjuvant chemotherapy followed by/combined with trastuzumab were included. The Kaplan-Meier method was used to estimate disease-free survival (DFS) and overall survival (OS). Hazard ratios (HR) and 95% confidence intervals (95% CI) were calculated using the Cox regression model. RESULTS: Of the 1,348 patients analyzed, 909 received chemotherapy alone and 439 received chemotherapy plus trastuzumab. The 3-year, 5-year and 10-year DFS rates were 83.70%, 76.38% and 68.94%, respectively, in the chemotherapy-alone cohort, and 90.21%, 86.19% and 83.45% in the chemotherapy plus trastuzumab cohort. The 3-year, 5-year and 10-year OS rates were 96.10%, 91.40% and 81.88% in the chemotherapy-alone cohort, and 98.17%, 94.91% and 90.01% in the chemotherapy plus trastuzumab cohort. The chemotherapy plus trastuzumab group had a significantly lower risk of disease recurrence and death than the chemotherapy-alone group (DFS: HR=0.50, 95% CI, 0.37−0.68; P<0.001; OS: HR=0.53, 95% CI, 0.34−0.81; P=0.004) after adjusting for covariates. In the 439 patients treated with trastuzumab, multivariate analysis suggested that lymph node positivity, higher T stages, and hormone receptor-negative status were significantly associated with higher risks of disease recurrence, and lymph node positivity and hormone receptor-negative status were significantly associated with higher risks of death. Grade 3/4 adverse events (incidence ≥1%) were more common in patients receiving trastuzumab (54.44%vs. 15.73%). CONCLUSIONS: Early-stage HER2-positive breast cancer patients treated with trastuzumab plus adjuvant chemotherapy have a significant survival benefit compared with chemotherapy-alone in real-world settings. Lymph node positivity, hormone receptor-negative status, and higher T stages may be associated with higher risks of recurrence, and effective therapy for patients with these factors is required.