Close relatives of women with a faulty version of the CHEK2 gene as well as bilateral breast cancer are at increased risk for breast tumors of their own, British researchers have reported. First-degree female relatives of women with bilateral breast cancer and a normal CHEK2 gene are already at high cumulative risk of breast cancer - 23.8% by age 80 compared with an expected cumulative risk of 7.9% for the population as a whole, according to Nicola Johnson, D.Phil., of the Institute of Cancer Research here. But when the faulty gene, dubbed CHEK2*1100delC, is also present, the rate more than doubles to 58.8%, Dr. Johnson and colleagues reported in the Oct. 28 issue of The Lancet.
