ERBB2 and breast cancer: However, HR+/HER2− breast cancer patients benefit less from chemotherapy than HER2+ or triple-negative breast cancer patients (6), and young age alone should not be a reason to expand chemotherapy indications in early breast cancer (7, 8) Therefore, it is important to identify patients who will not benefit from chemotherapy to avoid unnecessary chemotherapy in young patients with HR+/HER2− breast cancer.