ESR1 and ductal breast carcinoma in situ: Among these patients, 16 (70%) patients were diagnosed with triple-negative breast cancer (TNBC), five (22%) with luminal B breast cancer, and one (4%) with human epidermal growth factor receptor (HER)2+ ductal cancer in situ (DCIS), and in one (4%) patient, there was no histopathological data on estrogen receptor (ER), progesterone receptor (PR), or HER2 expression (Part D in S2 Fig).