The Efficacy of Pyrotinib as a Third- or Higher-Line Treatment in HER2-Positive Metastatic Breast Cancer Patients Exposed to Lapatinib Compared to Lapatinib-Naive Patients: A Real-... oleh D. J Ouyang, D. J Ouyang, Q. T Chen, M. Anwar, N. Xie, Q. C. Ouyang, P. Z. Fan, L. Y. Qian, G. N. Chen, E. X. Zhou, L. Guo, X. W. Gu, B. N. Ding, X. H. Yang, L. P. Liu, C. Deng, Z. Xiao, J. Li, Y. Q. Wang, S. Zeng, Shouman Wang, Wenjun Yi