ESR1 and neoplasm: Notably, after adjusting for patient age, tumor size, ER, HER2, NHG, Ki67 and adjuvant treatments in multivariable analysis, high CYP27A1 protein expression emerged as a strong and independent prognostic factor for a better DRFS among patients with ER+ tumors, associated with a 74% decrease in the incidence of DRFS events (HRadj = 0.26, 95% CI = 0.07–0.93).