Risk From Breast Cancer Gene Exaggerated

Finding May Lead to Better Understanding of Breast, Ovarian Cancer

From the WebMD Archives

Aug. 20, 2002 -- They call it the BRCA mutation, and it stands for BReast CAncer. But now it appears that BRCA mutations don't tell the whole story of inherited breast cancer risk.

Earlier studies suggested that a woman with one of two BRCA gene mutations had as much as an 85% chance of getting breast cancer during her lifetime. This has led many women with strong family histories of breast cancer to seek BRCA tests. If these tests are positive, some women choose surgery to remove still-healthy breasts and/or ovaries. Others may try to reduce their cancer risk by taking the drug tamoxifen.

Now, a report in the Aug. 21 issue of the Journal of the National Cancer Institute shows that these earlier studies were wrong. The way families were chosen for study mixed up the risks of BRCA mutations with risks from other, still-unknown factors. Though BRCA mutations remain important, they tell less than half of the cancer-risk story.

"I think that anybody with a BRCA mutation should be concerned about breast cancer and should be very careful to have routine mammograms," study author Colin B. Begg, PhD, tells WebMD. "But really invasive procedures like preventive mastectomy do not make sense in someone with a risk of less than 85%."

Begg, head of epidemiology and biostatistics at New York's Memorial Sloan-Kettering Cancer Center, says it's becoming clear that many factors influence breast cancer. His study, he says, should encourage researchers to go out and find more of these factors.

That's true, says Wylie Burke, MD, PhD, chairwoman of the department of medical history and ethics at the University of Washington in Seattle. Burke is co-author of a commentary article accompanying Begg's report in the JNCI. Burke says that the paper's findings are not a complete surprise. Instead, she says, they are a call to arms.

"It is true that some women with BRCA mutations may not be facing as high a risk as we thought," Burke tells WebMD. "But the main message is for researchers. We need to find those other factors. They may provide very important clues not only for women at high risk of breast cancer but for all women."