ERBB2 and breast cancer: The higher costs may be attributed to the aggressive BC care in young women because they are more likely to be diagnosed with BC stages II and III (stage 2 BC: 44.3 vs. 29.9%, respectively; stage 3 BC: 14.0 vs. 7.7%, respectively), triple-negative BC (21.2 vs. 13.8%, respectively), and HER2-positive (HER2+: 26.0 vs. 18.6%, respectively) compared to middle-aged women (50, 51).