A study of Jewish women in Ontario has found that many of the women who carry a genetic mutation that dramatically raises their risk of breast and ovarian cancer would be ineligible for DNA testing under current guidelines.
The findings, say the Women's College Hospital researchers, fuel their assertion that all Jewish women should be offered genetic risk testing.
Fro the study, more than 2,000 Jewish women of Eastern European origin, aged 25 to 80, were recruited and asked them to be tested for three mutations in two genes, known as BRCA1 and BRCA2.
They found 22 had a BRCA1 or BRCA2 mutation. That works out to about one in 100 or one per cent. In the general population, one in 400 individuals carries the mutations.
When the researchers then offered to test their sisters and adult daughters, eight of them also carried the genetic anomaly, according to results published in the Journal of Clinical Oncology. None of the women had developed cancer.
Yet none of the women had been referred for genetic screening by their health-care providers. 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.
Although 45 per cent of the women with mutations had been eligible for genetic testing based on their family history, none actually were, notes one of the study's authors, Dr. Kelly Metcalfe, an adjunct scientist at the Women's College Research Institute.
Metcalfe and principal author Dr. Steven Narod, director of the Familial Breast Cancer Research Unit at Women's College Hospital, believes that more women should receive genetic screening.
"We believe that genetic screening should be available to all Jewish women so we can prevent breast and ovarian cancers from striking those with a genetic predisposition," he said in a statement
Women of Ashkenazi Jewish descent have a four to five times higher risk of carrying a mutation than the general population, he said. And carriers of the mutations have a 70 per cent lifetime risk of developing breast cancer and up to 40 per cent chance for ovarian cancer. Women in the general population have about 12 per cent lifetime risk of developing breast cancer.
Among women of Ashkenazi Jewish ancestry (Jews of Eastern European origin), about 40 per cent of ovarian cancers and 12 per cent of breast cancers occur because of these mutations.
Women who carry one of the mutations can take medication, 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.
The study is now being extended to include up to 5,000 additional Jewish women. With funding from the Women's College Hospital Foundation, the study will offer genetic screening, through a saliva DNA test.
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.
