PIK3CA and neoplasm: They exhibited tumours with significantly lower grades (grade 1-2: 32% vs 12.1%; p < 0.001), more frequent lobular histology (8.9% vs 1.5%; p = 0.007) and PIK3CA mutations (27.6% vs 3.3%; p < 0.001), less basal-like phenotype (53.6% vs 73%; p < 0.001), BRCA1 promoter methylation (9.2% vs 35.9%; p < 0.001) and defects in PTEN (15.3% vs 34.1%; p = 0.009).