HER2-positive breast cancer patients receiving trastuzumab treatment obtain prognosis comparable with that of HER2-negative breast cancer patients

Tao Qin,* Zhongyu Yuan,* Roujun Peng, Bing Bai, Yanxia Shi, Xiaoyu Teng, Donggeng Liu, Shusen Wang

Department of Medical Oncology, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou, People's Republic of China

*These authors contributed equally to this work

Purpose: The efficacy of trastuzumab in Chinese breast cancer (BC) patients has rarely been reported. This study was designed to compare the clinical outcomes of HER2-positive BC patients receiving or not receiving trastuzumab treatment and HER2-negative BC patients.
Patients and methods: This study involved three groups of patients. The first group was 115 human epidermal growth factor receptor 2 (HER2)-positive BC patients treated with trastuzumab who were enrolled at Sun Yat-sen University Cancer Center between January 2002 and July 2010; the second group was a matched control group of 115 HER2-positive patients who did not receive trastuzumab treatment; the third group was a matched group of 115 HER2-negative patients who received conventional therapy in the adjuvant setting. The primary endpoint was 3-year and 5-year disease-free survival (3-DFS and 5-DFS, respectively). The Kaplan–Meier method, log-rank test, and multivariate Cox proportional hazard regression model were used for survival analysis. The differences in survival rates among the three groups were also analyzed according to two different periods: 2002–2006 and 2007–2010.
Results: The median duration of follow-up was 36 months (range, 12–111 months). The 3-DFS rates in the HER2-negative group, the HER2-positive group who received trastuzumab treatment, and the HER2-positive group who did not receive trastuzumab treatment were 82.6%, 89.6%, and 67.0%, respectively. The 3-DFS rate for the total study population was statistically significant (P < 0.001). Further analysis indicated a statistically significant difference in 3-DFS between either of the first two groups and the third group (P < 0.01), but the difference between the first two groups was not statistically significant (P = 0.157). Among the three groups, the 3-DFS rates during 2002–2006 did not have a significant difference compared with that during 2007–2010.
Conclusion: This study has further confirmed the efficacy of trastuzumab for HER2-positive operable BC in Chinese patients. It has also demonstrated that the 3-DFS and 5-DFS rates between HER2-positive patients receiving trastuzumab treatment and HER2-negative patients are comparable.

Keywords: breast cancer, HER2, trastuzumab, adjuvant treatment, survival analysis