In the largest collaborative study of 1483 MBC cases 99% were ER+ve, 82% PR+ve, 97% AR+ve and only 9% HER2+ve. There was an inverse relationship between AR positivity and grade: 71% grade I versus 46% of grade III. MIB1 status and Bcl2 expression have not been shown convincingly to be markers of prognosis. When 1474 MBC were subjected to IHC, 40% were luminal A, 54% luminal B, 5.5% HER2-enriched and 0.5% triple negative. Proteosomal investigation of MBC investigation in terms of activity of the kinase inhibitor proteins (KIPs) p27Kip1 and p21Waf1 reported that the latter was found in 70% of MBC compared with 29% of FBC. A male breast tumour-associated antigen MBTAA was associated with circulating antibodies in MBC cases but not in tumour-free males or FBC patients. In a comparison of gene expression in MBC specimens and FBC there were genomic gains more frequently in MBC but with fewer and two MBC genomic subgroups were proposed: male-complex and male-simple the latter being a male specific type.