Increased Risk of Breast Cancer Associated With CHEK2*1100delC

PURPOSE: CHEK2*1100delC heterozygosity has been associated with increased risk of breast, prostate, and colorectal cancer in case-control studies. We tested the hypothesis that CHEK2*1100delC heterozygosity in the general population increases the risk of cancer in general, and breast, prostate, and colorectal cancer in particular. PATIENTS AND METHODS: We performed a prospective study of 9,231 individuals from the Danish general population, who were observed for 34 years, and we performed a case-control study including 1,101 cases of breast cancer and 4,665 controls. RESULTS: Of the general population, 0.5% were heterozygotes and 99.5% were noncarriers. In the prospective study, multifactorially adjusted hazard ratios by CHEK2*1100delC heterozygosity versus noncarriers were 1.2 (95% CI, 0.7 to 2.1) for all cancers, 3.2 (95% CI, 1.0 to 9.9) for breast cancer, 2.3 (95% CI, 0.6 to 9.5) for prostate cancer, and 1.6 (95% CI, 0.4 to 6.5) for colorectal cancer. In the case-control study, age-matched odds ratio for breast cancer by CHEK2*1100delC heterozygosity versus noncarriers was 2.6 (95% CI, 1.3 to 5.4). The absolute 10-year risk of breast cancer in CHEK2*1100delC heterozygotes amounted to 24% in women older than 60 years undergoing hormone replacement therapy, with a body mass index of 25 kg/m2 or higher. CONCLUSION: CHEK2*1100delC heterozygosity is associated with a three-fold risk of breast cancer in women in the general population.