Researchers pinpoint new breast cancer susceptibility gene

LOS ANGELES (AP) _ Researchers have identified a gene that when mutated can lead to an elevated but modest risk of breast cancer. <br><br>The altered gene, called CHEK2 or CHK2, can double the estimated

Monday, April 22nd 2002, 12:00 am

By: News On 6

LOS ANGELES (AP) _ Researchers have identified a gene that when mutated can lead to an elevated but modest risk of breast cancer.

The altered gene, called CHEK2 or CHK2, can double the estimated 13 percent lifetime risk of breast cancer that U.S. women face, researchers said.

About 1 percent of people _ both women and men _ carry the mutated gene.

Carrying it does not necessarily mean someone is destined to develop breast cancer, the scientists stressed. Instead, the risk is comparable to that faced by women who have a mother or sister with breast cancer, who never have children or who experience menopause at a later age.

``CHK2 is not something anyone should go out and get tested for,'' said Michael Stratton, of the Institute of Cancer Research in London. Stratton is co-author of a report detailing the finding published online Sunday by the journal Nature Genetics.

The gene is also estimated to increase the risk of breast cancer in men tenfold. However, the cancer remains extremely rare in men, accounting for less than 1 percent of all breast cancer cases.

A pair of genes _ BRCA1 and BRCA2 _ remain the only genes linked to a significantly elevated risk of breast cancer. Carriers of those genes face a risk of developing inherited forms of the cancer as high as 85 percent.

In the study, an international group of researchers led by teams in the United Kingdom and Netherlands studied 1,071 breast cancer patients who had a family history of the disease, but who hadn't inherited BRCA1 or BRCA2. Their histories were compared with a group of 1,620 healthy individuals.

In the patient group, 5.1 percent of women and 13.5 percent of men had inherited the faulty version of CHK2, compared with 1.1 percent overall in the control group.

Having the bad CHK2 did not raise the cancer risk for women who also had abnormal versions of BRCA1 and BRCA2, researchers said.

Healthy copies of all three genes are believed to be involved in genetic repairs within cells.

Dr. Kenneth Offit, of the Memorial Sloan-Kettering Cancer Center in New York, stressed that the findings are of limited relevance to the clinical treatment of breast cancer.

``While these findings are of scientific importance, their use for patient care is limited by the relatively low predictive power of these tests, compared to other known markers _ for example, BRCA mutations,'' said Offit, who was not involved in the study.