Mutations in the BRCA1 and BRCA2 genes cause hereditary breast-ovarian cancer syndrome, with a greatly increased risk of certain cancers (particularly breast cancer) in affected individuals. What is less commonly understood is that men who inherit mutations in these genes may also develop breast cancer, albeit to a lesser degree than female mutation carriers. Male breast cancer is much rarer than in women, but inherited mutations, particularly in the BRCA2 gene, are a significant cause.
A new paper in the Journal of Medical Genetics reports findings from a study of more than 300 families from parts of the UK with BRCA2 mutations to determine the risk of breast cancer in male BRCA2 carriers.
Over 900 men were identified as first degree relatives of known BRCA2 mutation carriers. The researchers identified previous cases of breast cancer among these men, and followed them over time to identify new cases. They calculated that breast cancer risk among such men was 7.1% by age 70 years and 8.4% by age 80 years, concluding that awareness of breast cancer (to boost early diagnosis) in men was important for affected families [Evans DGR et al. (2010)J Med Genet doi:10.1136/jmg.2009.075176].
Comment: This study provides a useful estimate of the risk of breast cancer among male relatives of BRCA2 mutation carriers at 6-9%. This compares with a population risk of just 0.1% (see BBC news), underlining the importance of making risks known to men in affected families, as suggested by the authors. Although some assumptions are made in the calculations such as that all men from the study who developed breast cancer were necessarily mutation carriers, it is nevertheless the largest study of the kind to date.