Association between the BRCA2 N372H variant and male breast cancer risk: a population-based case-control study in Tuscany, Central Italy.

Background: Male breast cancer (MBC) is a rare disease and little is known about its aetiology. Germ-line mutations of BRCA2 and, at lower frequency, of BRCA1 are implicated in a relatively small proportion of MBC cases. Common polymorphic variants in BRCA1 and BRCA2 genes may represent breast cancer (BC) susceptibility alleles and could be associated with a modestly increased risk of MBC at population level. Considering the relevant role of BRCA2 in MBC, we investigated whether the BRCA2 N372H variant, representing the only common non-synonymous polymorphism in BRCA2, might modulate the risk of BC in male populations.

Methods: A case-control study was performed comparing a population-based series of 99 MBC cases, characterized for BRCA1 and BRCA2 mutations, with 261 male population controls, all residing in Tuscany, Central Italy. All MBC cases and controls were genotyped for the BRCA2 N372H allele by TaqMan allelic discrimination assays. To evaluate the genotype specific risk of the BRCA2 N372H variant, MBC carriers of germ-line BRCA1/2 mutations were excluded from the analyses.

Results: No association emerged in univariate and age-adjusted analyses. Age-specific analyses suggested an increased risk for the HH homozygous genotype in subjects younger than 60 years. A statistically significant interaction emerged between this genotype and age (p = 0.032). When analyses were restricted to MBC cases enrolled in the first 4 years following diagnosis, a recessive model showed a significantly increased risk of MBC in HH subjects younger than 60 years (OR = 5.63; 95% CI = 1.70;18.61).

Conclusion: Overall, our findings, although based on a relatively small series, suggest that the BRCA2 HH homozygous genotype might be positively associated with an increased risk of MBC in men younger than 60 years.