We examined tumoral characteristics and clinical outcomes among pre- and postmenopausal patients with BC (n = 1628 and 3457, respectively), stratified into ER+/HER2 negative (HER2-) (n = 3333) and TNBC (n = 1752) subtypes across HSD3B1 genotypes. The gene discussed is HSD3B1; the disease is breast cancer.