Stratification analyses uncovered that CMTM6 protein expression in HER2+ BC tissues from trastuzumab-treated patients was positively associated with clinical T stage (P = 0.007), clinical N stage (P = 0.039), metastasis (M classification, P = 0.023), pathological grade (P = 0.041), ER status (P = 0.016), relapse status (P < 0.001) and survival status (P < 0.001; Table 1). The gene discussed is ERBB2; the disease is breast cancer.