Male breast cancer (MBC) is very rare and accounts for <1% of all breast cancers. Compared with female breast cancer, MBC has been poorly characterised at the molecular level. Clinical management of MBC is currently guided by our greater understanding of the disease in females, but whether MBC is a distinct disease is not known.

Moelans et al. obtained DNA from 45 formalin-fixed paraffin-embedded (FFPE) MBCs with matched normal tissues, as well as 90 unmatched MBCs (52 FFPE, 38 fresh-frozen). DNA was subjected to massively parallel sequencing, targeting all exons of 1943 cancer-related genes. Mutations and copy number alterations were compared with publicly available female breast cancer data.

The genomic landscape of MBC shared similarities with female disease, with common somatic mutations in PIK3CA and GATA3 and 40% of the most frequently amplified genes overlapping between the sexes. Somatic mutations in genes regulating chromatin function and homologous recombination deficiency-related signatures were more prevalent in MBC. Amplifications in MDM2 were more frequent in MBC than in female disease and this correlated with protein expression and predicted poor outcome.

MBC shares similarities with female breast cancer, but clear differences exist that should be accounted for in the classification and management of this disease.

Read the full article in Endocrine-Related Cancer 26 779–794