ESR1 and breast carcinoma: Regarding hormone receptors, male patients with breast cancer have a higher proportion of ER and PR positivity and a lower proportion of HER2 positivity compared to female patients, which are findings consistent with our case.1,16 Male breast cancer patients with the hormone receptor–positive/HER2-negative subtype have been shown to have worse overall survival compared to stage- and subtype-matched female breast cancer patients.2,17