In a phase II randomized controlled trial (RCT) of pyrotinib in HER2-positive advanced breast cancer patients, a combination of pyrotinib and capecitabine significantly increased the ORR (78.5% vs. 57.1%) and extended progression-free survival (PFS) (18.1 vs. 7.0 months) as compared with combined lapatinib and capecitabine therapy. Here, ERBB2 is linked to breast cancer.