BRCA1/2

[Lola]

Im one of those women!

[Gail]

Breast cancer risk not equal in families16:37 AEST Tue Nov 1 2011


Not all women from families with a history of breast cancer face a high risk of developing the disease, a major international study has found.

The finding has poured cold water on previous research which claimed women who do not carry a genetic mutation linked to breast cancer were just as likely to develop the disease as close relatives who do carry the gene defect.

The latest study, the biggest of its kind, was based on an analysis of 3000 families from Australia, Canada and the United States with a history of breast cancer.

It found women without the genetic mutation known as BRCA1 or BRCA2 despite their mothers, sisters, aunts or grandmothers being carriers were no more likely than women in the general population to develop breast cancer.

University of Melbourne professor John Hopper, who led the Australian part of the study, said he hoped the finding would clear up misunderstandings about the risk of developing breast cancer for women in families with a history of the disease.

He said the confusion had caused a type of "survivor's guilt" among some women who had tested negative for the mutation despite their close relatives being carriers.

"They thought that even though they tested negative there was still something going on," Prof Hopper said.

"But now we are saying that women don't need to be anxious if they are in a family with the mutation.

"If you are in a family and you don't carry that mutation, unless there's a lot of other people in the family with breast cancer that isn't explained by that mutation, then you should be dealt with like the general population in terms of assessing your risk."

One in 500 Australian women are estimated to carry BRCA1 or BRCA2, giving them a five to 20 times higher risk of developing breast or ovarian cancer compared to the average healthy woman.

A British study published in 2007 claimed mothers, sisters and daughters in families with a history of the BRCA1 and BRCA2 mutations had a two to five-fold increased risk of developing breast cancer even if they weren't carriers of the faulty gene.

The finding sparked some confusion among genetic counsellors about whether to advise women with a family history of the mutations, but who weren't carriers, to still undergo extra screening checks for the disease.

However the researchers behind the latest study said the extra checks were probably not required.

"These results support the standard clinical practice of advising noncarriers (of the mutations) that they do not have any increase in breast cancer risk attributable to the family-specific BRCA mutation and, in the absence of other strong risk factors, should follow general population guidelines for breast cancer screening," they wrote in their paper, published on Monday in the Journal of Clinical Oncology.

The study also revealed that women who carry the BRCA1 and BRCA2 mutations account for only 3.4 per cent of the female populations in the three countries which took part in the research.

However the women in that high risk group account for 32 per cent of all breast cancer cases in those countries.