All Jewish women should be offered DNA testing to determine if they carry a genetic mutation that dramatically raises their risk of developing both breast and ovarian cancer, a group of researchers says.
In a study published Monday, researchers at Women's College Hospital in Toronto found that about one per cent of Jewish women in Ontario carry mutations in the BRCA1 or BRCA2 genes, yet more than half of those identified would be ineligible for DNA testing under current provincial guidelines.
Women of Ashkenazi Jewish descent (Jews of Eastern European origin) have a four to five times higher risk of carrying a BRCA mutation than the general population - and carriers have an 80 per cent chance of developing breast cancer and a 20 to 40 per cent chance of ovarian cancer in their lifetime.
Currently, women are only eligible for genetic testing for BRCA1 and BRCA2 in Ontario if they have been referred by a physician due to a strong family history of the disease or have already been diagnosed with breast or ovarian cancer. Most other provinces have similar criteria.
"Personally, I think that attitude which is predominant in most provinces is archaic," said principal author Dr. Steven Narod, director of the Familial Breast Cancer Research Unit at Women's College.
"It doesn't make sense from a public health perspective," he said. "My goal is to prevent the cancer, not identify the genetics after. The only way I'm going to use genetics in a preventive setting is to be able to identify the carriers of the mutation before they get cancer - and then we're going to intervene and prevent that cancer."
About 40 per cent of ovarian cancers and 12 per cent of breast cancers in women of Ashkenazi Jewish ancestry occur because of these mutations, but are potentially preventable.
Women who carry one of the mutations can take a drug such as tamoxifen to lower their risk of breast cancer or opt for a full mastectomy. To reduce the risk of developing ovarian cancer, women can take oral contraceptives or have their ovaries removed.
To conduct the study, published online in the Journal of Clinical Oncology, the researchers used a 2008 newspaper article to recruit more than 2,000 Jewish women aged 25 to 80, who volunteered for genetic testing.
Out of 2,080 women who signed on for the study, 22 were found to have a BRCA1 or BRCA2 mutation. Testing was then offered to their sisters and adult daughters, and eight of them were also found to carry the genetic anomaly.
None of these women had previously been referred for genetic screening by their health-care providers, said Narod, noting that what was exciting for the researchers was of the 30 women found to have a mutation, none had developed cancer.
Lead author Kelly Metcalfe, an adjunct scientist at the Women's College Research Institute, said the study identified two major concerns with current genetic screening guidelines.
"The first is that over half of the women we identified with a mutation would never have known that they were at an increased risk of cancer because they were not eligible for genetic testing outside of this study," she said.
"The second concern was that although 45 per cent of the women with mutations were eligible for genetic testing based on their family history of cancer, none were referred by their health-care provider for screening."
Genetic counsellor Jenna Scott, clinical co-ordinator of the B.C. Cancer Agency's Hereditary Cancer Program, said the study raises some interesting issues and challenges the one-size-fits-all approach to genetic testing.
"I think it raises a really important question of why were those women not referred (by their primary-care providers). Or were they not interested in referral because they found it cumbersome or there were too many barriers to getting into a clinic," Scott said from Vancouver.
"We need to critically look at how we provide genetic services ... so that patients are getting the best care possible," she said, but stressed that not all women would choose to have the genetic testing, despite the potential risk.
"I don't think whether it's B.C. or the programs in Ontario or internationally, people are probably not going to change their clinical protocols overnight in response to this one (study). I think we're all very interested in it, but I don't think we know the full impact of testing in this dynamic."
Dr. David Fleiszer, a surgeon at the McGill University Health Centre, said other "founder populations," including a French Canadian group, also have an elevated risk of carrying a BRCA mutation and also might benefit from genetic testing.
"Starting with the Ashkenazi Jews is a good place to start, but personally I don't think we should be excluding some of the other identified high-risk groups," he said from Montreal. "I would think the same sort of policy would apply to them, just as well as anybody."
Narod said his research team has received funding to expand the study to include up to 5,000 Jewish women. Like the initial study phase, it will offer genetic screening through a saliva DNA test, plus counselling for those found to be positive for a mutation.
To take part in the study, adult Jewish women in Ontario with or without a known family history of breast or ovarian cancer can contact Women's College Hospital at 416-351-3795 or visit the website at www.womensresearch.ca/jewishstudy.