ERBB2 and breast cancer: Among HER2-targeted agent users, total unadjusted all-cause and breast cancer-related expenditures were significantly lower for HT+ (all-cause: $12,391 versus $15,934, P < 0.001; breast cancer-related: $8,092 versus $9,103, P < 0.01) and recurrent patients (all-cause: $13,446 versus $15,223, P < 0.01; breast cancer-related: $7,510 versus $10,409, P < 0.001) compared to their respective counterparts (Table 6).