ERBB2 and breast cancer: The aims of our study were as follows: (1) to estimate the cost-effectiveness of pyrotinib plus capecitabine versus lapatinib plus capecitabine in patients with previously treated HER2-positive metastatic BC from the perspective of the Chinese healthcare system; and (2) to validate the above-mentioned hypothesis that the national medical insurance price negotiation could pose positive impact on the economics of pyrotinib.