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BRCA Breast Cancers Aren't More Deadly

Study Shows Mutations in BRCA Genes Don't Influence Survival Rates
WebMD Health News
Reviewed by Louise Chang, MD

July 11, 2007 -- It appears that breast cancer patients with BRCA mutations are as likely to survive their disease as women who don't carry the inherited breast cancer genes.

Researchers compared cancer-specific survival outcomes among Israeli women with BRCA1 or BRCA2 gene mutations to women without the genes in the new study, published in the July 12 issue of The New England Journal of Medicine.

They found no difference in survival among the two groups, challenging the common belief that breast cancers occurring among BRCA carriers are more deadly than cancers in noncarriers.

"We know that women with BRCA1 and BRCA2 mutations tend to show up with bad prognostic factors -- characteristics that suggest they are at very high risk," researcher Gad Rennert, MD, PhD, tells WebMD. "But our results suggest the outcomes among these women are often much better than would be expected."

BRCA Mutations Uncommon

Inherited gene mutations account for just 5% to 10% of all breast cancers diagnosed in the U.S. BRCA1 and BRCA2 mutations are the most common ones linked to hereditary breast cancer and ovarian cancer, but the lifetime risk of developing breast cancer is between three times and seven times higher for carriers than noncarriers, according to the National Cancer Institute.

People of Ashkenazi Jewish descent are five times more likely to have inherited BRCA mutations than the general population.

Because Israel has a very high concentration of Ashkenazi Jews as well as a national breast cancer registry, Rennert and colleagues from the nation's National Cancer Control Center were able to compare long-term breast cancer outcomes among a large group of BRCA carriers and noncarriers.

The researchers first tested DNA from stored tumor specimens obtained from breast cancer patients treated in Israel in 1987 and 1988 to determine the incidence of BRCA mutations.

They then reviewed the medical records of the women from whom the specimens were collected for a minimum of 10 years after diagnosis.

A BRCA1 or BRCA2 mutation was identified in 10% of the samples tested from women who were of Ashkenazi Jewish descent, and the 10-year follow up revealed that women who carried a BRCA mutation and women who were not carriers had similar survival rates.

Rennert says the findings should serve to reassure women who are at high risk for developing breast cancer because they carry a BRCA mutation.

He noted that classic predictors of poor outcome, such as tumor size at diagnosis and lymph node status, did not appear to impact survival among the women in the study.

"Most [BRCA carriers] who develop breast cancer will survive their disease," he says. "That is an important message to get out to women and their doctors."

BRCA Mutations and Research

Patricia Hartge, ScD, who wrote an editorial accompanying the study, calls the findings "generally reassuring" for women who carry BRCA mutations.

The National Cancer Institute official says that as more genes linked to individual cancers are identified, more researchers will examine the role of these genes in cancer outcomes.

She writes that it may soon become routine to re-evaluate clinical trial results with genetics in mind.

"There is an argument that 2007 has been the year of the genome in cancer," she tells WebMD. "Very soon I think we well see an explosion of studies examining the influence of genes in treatment outcomes."

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