The BRCA1 and BRCA2 mutations are linked to aggressive hereditary breast cancers. (CBC)

About one per cent of Jewish women in Ontario carry a genetic mutation that makes them more susceptible to ovarian and breast cancer, but many are not on the Health Ministry's list of candidates for genetic testing, a new study suggests.

The study asked whether women in the Jewish community were interested in genetic testing even if they had no personal or family history.

Of the 2,080 women of Ashkenazi ancestry who applied to be research subjects, 22 were found to have a BRCA1 or BRCA2 genetic mutation, Dr. Kelly Metcalfe of Women's College Research Institute in Toronto and her colleagues reported in Monday's online issue of the Journal of Clinical Oncology.

The BRCA1 and BRCA2 mutations are linked to aggressive hereditary breast cancers, but only account for about 15 per cent of all cases.

Those who tested positive face an 87 per cent risk of developing breast cancer compared with the average women's risk of 11 per cent. Their risk of ovarian cancer is high, too, at 40 per cent, compared to the one per cent risk most other women face.

Currently, women in Ontario are only eligible for genetic testing for BRCA1 and BRCA2 if they have been referred by their doctor because of a strong history of the disease, or have a personal history with breast or ovarian cancer.

Over half of the women identified with a mutation would never have known they were at an increased risk of cancer because they were not eligible for genetic testing outside of this study, Metcalfe said.

Of the 45 per cent of women with mutations who were eligible for genetic testing based on their family history, none was referred for the screening.

'I was blank'

Judy Kowal of Richmond Hill believes the only reason her ovarian cancer was caught was because she was screened. Her diagnosis came within weeks of learning she carried the mutation. She had a hysterectomy in early September.

"I was blank," Kowal recalled, noting two of her brothers were also tested and the results were negative. "I had no knowledge about it." She showed no symptoms of ovarian cancer, which is often called a silent killer for that reason.

The study's results may give the Ontario Health Ministry evidence to include Jewish women in genetic screening.

"We can almost look into a crystal ball and say, 'We know that you're at a very high risk of breast cancer. Let's do something about it so that it never happens,' " Metcalfe said.

About 40 per cent of ovarian cancers in Jewish women and 12 per cent of breast cancers are the result of these three mutations.

Women who test positive may be offered:

• Preventive drug therapy with tamoxifen for five years, which is thought to lower the chances of developing breast cancer for women at high risk.
• Use of oral contraceptives to reduce the chance of developing ovarian cancer.
• Preventive surgeries include removal of one or both breasts and removal of the ovaries.

The study is being extended to include up to 5,000 Jewish women across the province who will be offered the genetic screening. The test involves taking a saliva sample to check for three inherited breast cancer gene mutations.

Only women with a known strong history of cancer are screened in most provinces, but Jewish cancer support groups say every woman in the community should be eligible for the test.

"They should be aware of it and possibly talk to their doctor about it, find out about their family history," said Elizabeth Elrich of the L'Chaim Cancer Support Group for Jewish Women in Toronto.

People who are interested in participating may call (416) 351-3795 or go to www.womensresearch.ca/jewishstudy for more information on how to get the test.

The Women's College Research Institute is offering the test free for eligible Ontario residents.