For the first time in Canada, Jewish women will be offered the chance to alter their genetic destiny by taking a test – at no cost to them – that will determine whether they are at high risk of developing breast and ovarian cancers.
By screening for three inherited breast cancer gene mutations common to those of Ashkenazi Jewish ancestry, Women's College Research Institute scientists have an ambitious goal: to prevent the dreaded disease before it strikes.
They plan to do that by offering adult Jewish women in Ontario, with no known family history of breast or ovarian cancer, the blood test to screen for three specific mutations of the BRCA1 and BRCA2 genes, beginning this Thursday. Jewish women with a family history of breast or ovarian cancer who have never been tested are also eligible.
If expanding genetic testing to this group proves worthwhile, it could alter the way the testing is offered across Canada by recognizing one's inherent risk of cancer, simply due to ancestry.
The goal of the test is “to prevent cancer,” said Steven Narod, director of the familial breast cancer research unit at Women's College Research Institute in Toronto. One in 44 Ashkenazi Jewish people carry the mutation, he noted; in the general population, an estimated one in 400 individuals carries a mutation in BRCA1 or BRCA2.
For Ashkenazi women, a group with mainly Central and Eastern European ancestry, the test could reveal a risk they never knew they had. Sarah Neumin, a 44-year-old psychotherapist in Toronto, said there was no breast cancer in her family – until her sister was diagnosed with it three years ago. Ms. Neumin has since tested positive for a mutation of the BRCA1 gene that she inherited from her father.
“We had no cancer at all in the family,” said Ms. Neumin, who now undergoes regular screening for breast and ovarian cancer. “We didn't have a lot of females in our extended family who didn't die in the Holocaust. You can't really do a family tree because a lot of people really didn't live that long.”
Canada's Jewish population is overwhelmingly Ashkenazi: 327,360 out of a total of 370,055, according to figures from Charles Shahar, chief researcher of the national census project for UIA Federations Canada. And about half of the Ashkenazi Jewish population – 165,175 – live in Toronto.
Based on the one-in-44 risk factor, 7,440 Ashkenazi Jewish Canadians are unwitting carriers of BRCA1 or BRCA2 genetic mutations.
Until now, Jewish ancestry was not enough to warrant testing for hereditary breast and ovarian cancer anywhere in Canada; nor is there any known organized population screening of Jewish women in the United States. Several years ago, Dr. Narod, who is also a University of Toronto professor, did a trial for recurring mutations among Polish women similar to the one on Jewish women starting next week.
Rabbi Jennifer Gorman, who is also director of youth activities for the United Synagogue of Conservative Judaism, Eastern Canada region, said she can see the test one day being offered the way screening for Tay-Sachs, a fatal genetic lipid storage disorder, is to couples of Jewish ancestry.
“The rate of this gene is so high,” she said. “It will be one of the tests that is normally done.”
A genetic crystal ball
The test is for three genetic mutations that recur in the Jewish population, due to the so-called founder effect, which occurs when a new colony is started by a few members of the original population, often due to geographic or religious isolation.
According to researchers, 40 per cent of today's Ashkenazi Jewish population arose from a group of four founding mothers, who lived somewhere in Europe within the past 2,000 years.
