A study of more than 9,000 Danish residents shows that a specific variation in the CHEK2 gene may triple a woman's risk of developing breast cancer in her lifetime. The study - the first to examine the prevalence of the CHEK2 mutation in the general population and the associated cancer risk - is published in the Journal of Clinical Oncology.
"Our study shows that women in the general population who carry a specific CHEK2 mutation are three times as likely as women without the mutation to develop breast cancer," said Borge G. Nordestgaard, MD, Professor and Chief Physician, Department of Clinical Biochemistry, Herlev University Hospital, Denmark, and lead author of the study. "The findings suggest that CHEK2 could serve as a useful biomarker for identifying women who would benefit from heightened, regular screening for breast cancer."
CHEK2, which belongs to a class of genes known as "tumor suppressors," is responsible for repairing DNA damage and preventing the uncontrolled division of cells, which can lead to cancer. In this study, researchers looked for a specific mutation, known as CHEK2*1100delC, which impairs the gene's ability to fix damage to DNA.
Previous case-control studies have shown an association between this specific CHEK2 mutation and breast, prostate, and colorectal cancer. Researchers designed this study to assess the prevalence of the mutation in the population at large and to examine its impact on cancer risk.
Dr. Nordestgaard and his colleagues randomly selected 9,231 Danes who had participated in the Copenhagen City Heart Study--a cohort of more than 20,000 Danish men and women that followed participants for an average of 34 years for cancer development.
The researchers found that 0.5% of all participants carried the CHEK2 mutation. Among women who carried the CHEK2 mutation, 12% developed breast cancer, compared to 5% of non-carriers. Adjusting for other factors, such as age, body mass index, and use of hormone replacement therapy, researchers found that women who carried the mutation were 3.2 times as likely as women who had normal CHEK2 genes to develop breast cancer. Those most at risk were mutation carriers on hormone replacement therapy who were more than 60 years old and overweight--who had a 24% chance of developing the disease within 10 years. The researchers found no statistically significant association between the CHEK2 mutation and prostate, colorectal, or general cancer risk.