BRCA1- and BRCA2-associated breast cancer tumours have also been reported to have different pathological characteristics from one another, and also from sporadic and other familial tumours (Breast Cancer Linkage Consortium, 1997; Lakhani et al, 1998; Lakhani et al, 2000; Lakhani et al, 2002). This evidence concerns the gene BRCA1 and breast cancer.