Peripheral cytotoxic T lymphocyte predicts first-line progression free survival in HER2-positive advanced breast cancer oleh Xiao-Ran Liu, Jian-Jun Yu, Guo-Hong Song, Li-Jun Di, Han-Fang Jiang, Ying Yan, Xu Liang, Ru-Yan Zhang, Ran Ran, Jing Wang, Han Bai, Shi-Dong Jia, Hui-Ping Li