ESR1 and neoplasm: Although some studies have reported age [6–9], site [6, 10, 24], ER positivity [7, 24], PgR positivity [8, 24], HER2 positivity [25] as predictors of SLNM, the most commonly reported predictors are tumor size [6–10, 24, 25], lymphatic invasion [6–8, 24, 25], and pathological nuclear grade [6–10, 24, 25].