ERBB2 and breast carcinoma: For HR + /HER2- breast cancer patients with ≥ 4 positive lymph nodes, adding 2 years of abemaciclib to standard adjuvant ET is strongly recommended; for patients with 1–3 positive lymph nodes and high-risk features (e.g., histological grade 3 or tumor size > 5 cm), 2 years of abemaciclib is also advised.