Purpose: To investigate whether or not a genetic variant in BARD1 (Cys557Ser) contributes to early-onset breast cancer in Poland, or modifies the risk of breast cancer in women with an inherited predisposition to breast cancer.
Experimental design: We studied 3,188 unselected Polish women with breast cancer and 1,038 healthy controls. All women were genotyped for the BARD1 Cys557Ser variant and for known founder mutations in BRCA1 (three mutations), CHEK2 (four mutations), and NBS1 (one mutation).
Results: A BARD1 variant was seen in 150 of 3,188 breast cancer cases (4.7%) and in 40 of 1,038 controls (3.8%) (OR = 1.2; 95% CI = 0.9-1.7). The risk associated with the BARD1 variant was not significantly greater in women with familial cancer (OR = 1.5; 95% CI = 0.8-2.7), or with an inherited mutation in BRCA1 (OR = 0.9; 95% CI = 0.4-2.2), CHEK2 (OR = 1.0; 95% CI = 0.5-2.1), or NBS1 (OR = 1.3; 95% CI = 0.2-10.2). Modest associations were observed among the subgroups of women with very early onset breast cancer (OR = 2.9; 95% CI = 1.2-7.1) and with medullary breast cancer (OR = 1.8; 95% CI = 0.9-3.7).
Conclusion: There was no clear association between the presence of the BARD1 Cys557Ser allele and breast cancer in Poland. Furthermore, the BARD1 Cys557Ser allele does not appear to modify the risk of breast cancers among carriers of BRCA1 mutations, or of other predisposing mutations. The allele may predispose to breast cancers of certain histologic subtypes, but further studies are needed to confirm these findings.