Patients with HER2-targeted agents had the highest unadjusted total PPPM healthcare expenditures for all-cause and breast cancer-related services among the three treatment cohorts, amounting to $14,105 PPPM for all-cause expenditure and $8,585 for breast cancer-related services (all P < 0.001) (Table 5). This evidence concerns the gene ERBB2 and breast carcinoma.