BRCA1 and cancer: In BRCA1 families, patients whose cancer was diagnosed when they were under 50 years of age differed significantly from those diagnosed at 50 years or older in the presence of grade 3 tumours (84.4% vs 47.1%, P = 0.009), ER-negativity (83.3% vs 25%, P = 0,001), and p53-positivity (50.0% vs 7.7%, P = 0.014) (Table 1).