A prospective study by Colleoni et al. that included 1427 women <50 years of age found a larger proportion of ER- (38.8% vs. 21.6%; p < 0.001), PR- (49.1% vs. 35.3%, p < 0.001), vascular or lymphatic invasion (48.6% vs. 37.3%; p = 0.006), and pathologic grade 3 tumours (61.9% vs. 37.4%; p < 0.0001) in women aged <35 years compared to those aged 35–50 years, respectively [196]. This evidence concerns the gene PGR and neoplasm.