ESR1 and invasive breast carcinoma: The American Society of Clinical Oncology, the American Society of Radiation Oncology, and the Society of Surgical Oncology [17] recommend that RT be applied to all patients with invasive breast cancer treated with breast-conserving surgery, except for those over 70 years of age and estrogen receptor (ER) positive, grade I. While the National Institute for Health and Care Excellence (NICE) [18] defines the group in which RT should be applied, it recommends adjuvant RT to all patients with positive axillary lymph node involvement after mastectomy.