November 1, 2011

Breast Cancer Study Debunks BRCA Research

(Ivanhoe Newswire) — The largest study of its kind shows that women related to a patient with breast cancer caused by a hereditary mutation, but who don´t have the mutation themselves, have no higher risk of developing cancer than relatives of patients with other types of breast cancer. This contradicts previous research conducted four years ago that said that a familial BRCA mutation in and of itself was a risk factor.

"The results are encouraging and reassuring," Allison Kurian, MD, assistant professor of oncology and of health research and policy and first author of a paper, was quoted as saying. She and her colleagues, including senior author Alice Whittemore, PhD, professor of health research and policy, said their findings support the current practice of advising so-called non-carriers that there is no increase in risk attributable to their family-specific BRCA1 or BRCA2 mutation.

The study doesn't dispute that women who have relatives with any type of breast cancer have a greater risk of contracting the disease compared to those with no cancer-stricken relatives.

A study in 2007 had compared relatives of BRCA carriers with women in the general population, and Kurian and her colleagues thought this might have created high estimates of the non-carriers' risk. For one reason: Women in a family with a known BRCA mutation are more likely to receive more intensive screening, and thus be more likely to be diagnosed with breast cancer than women in the general population.

The researchers sought, then, to compare cancer risk in non-carriers with a control group of relatives of cancer patients without the mutations. For the study they used data from population-based cancer registries provided by co-investigators from the Cancer Prevention Institute of California, the University of Melbourne in Australia and the University of Toronto in Canada to look at 3,047 families. Of the total, 160 families had BRCA1 and 132 had BRCA2 mutations.

When comparing the groups of relatives, they found no evidence of an increased breast cancer risk for non-carriers compared with the control group. The authors note that this finding supports "evidence-based practice guidelines [that] currently recommend that non-carriers be screened according to standard protocols for their age and other risk factors."

The findings should put to rest questions about risk based on a familial BRCA mutation. But Kurian added, "It's important for patients and clinicians to remember this doesn't rule out other risk factors, which might increase a non-carrier's probability of getting breast cancer."

SOURCE: Journal of Clinical Oncology, published online October 31, 2011