Association of the BRCA1 promoter polymorphism rs11655505 with the risk of familial breast and/or ovarian cancer.

Germline mutations in the BRCA1 tumor suppressor gene predispose affected individuals to breast cancer; however, incomplete cancer penetrance and the presence of phenocopies in BRCA1 families also indicate genetic and environmental modifiers of breast cancer risk. In this study, we have tested the single nucleotide polymorphism rs1655505 of the BRCA1 promoter, as candidate for the modifier of breast cancer risk. The polymorphic variants were genotyped in BRCA1-negative (729), familial breast and/or ovarian cancer cases (FBOC), including cases with a reported maternal history (154), nonfamilal (sporadic) cases (600), hereditary breast/ovarian cases with BRCA1 mutations (190) and population controls (1,590) from Central Poland. An association with the risk of FBOC was observed for the minor (T) allele and (TT) genotype (T: p = 0.006, OR = 1.40, 95% CI = 1.10-1.79; TT: p = 0.001, OR = 2.23, 95% CI = 1.37-3.62) in female cases with a reported maternal history, specifically in women with the onset of disease after 50 years of age (T: p = 0.004, OR = 1.77, 95% CI = 1.20-2.62; TT: p = 0.001, OR = 3.7, 95% CI = 1.62-8.46). The presented evidence suggests a need to conduct larger studies on the association between genetic variations at the BRCA1 promoter and the breast cancer risk, according to maternal/paternal lineage.