ERBB2 and neoplasm: Studies with grade 2B evidence (weak recommendation) have suggested that the omission of RT might be considered in women ≥65 years old with node-negative, hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative primary tumors up to 3 cm, for whom endocrine therapy is planned [8,9,10,11,12]; alternatively, administering RT to these women is also reasonable depending on their values and preferences, and the biologic features of the tumor.