News

Screening for hereditary breast and ovarian cancer genes in Ontario Jewish women

May 26, 2008

Please note, due to overwhelming demand, this study is full and cannot accept any more participants. If you would like your name put on a waiting list, in the event the study is expanded, please email your name and phone number to: narodstudy@wchospital.ca.

Genetic testing is at the centre of a new Canadian research project, which looks at Jewish women's greater tendency to carry the BRCA1 and BRCA2 genes. The presence of these genes indicates a higher risk of developing breast and ovarian cancer.

About 5 percent of women in Canada with breast cancer and about 12 percent of women with ovarian cancer are born with an inherited genetic predisposition to cancer. In some populations, there is more hereditary breast/ovarian cancer than in others. This is true for the Jewish population.

This genetic tendency to develop cancer can be checked with a simple blood test.

The Familial Breast Cancer Research Unit at Women’s College Research Institute in Toronto is using this test as part of a research study of a group of adult Jewish women in Ontario who signed up in order to find out their mutation status. These included those without a personal or family history of cancer.

This study drew a larger than anticipated body of participants, and the recruiting phase is now closed.

A research team led by Dr. Steven Narod, director of the Familial Breast Cancer Research Unit, will evaluate how common mutations are among the Jewish population, and whether or not it is possible to identify women with a genetic predisposition to developing cancer who otherwise might not come to the attention of the medical community.

Both Ashkenazi and Sephardi Jews may inherit a mutation, but mutations are more common in Ashkenazis (Jews of Eastern European origin). In this group, about one in 45 men or women carry a genetic predisposition to breast and ovarian cancer.

Among women who are BRCA1 mutation carriers, up to 70 percent will develop breast cancer by age 70 (compared to 7 percent of women in the general population); approximately 40 percent will develop ovarian cancer by age 70 (compared to 1.5 percent of women in the general population).

For individuals who have a mutation identified in the breast cancer susceptibility gene BRCA2, both women and men have a genetic susceptibility to develop breast cancer. Among women who are BRCA2 mutation carriers up to 70 percent will develop breast cancer by age 70.

It is estimated that women who have a BRCA2 mutation are at increased risk of developing ovarian cancer, approximately 15 to 20 percent by age 70. Men have an increased risk of developing prostate cancer. Both men and women have a slightly higher chance of developing pancreatic cancer, melanoma, stomach cancer and possibly colon cancer.

For women who are BRCA1 or BRCA2 mutation carriers, a range of options is available (depending on the wishes of the individual). Current options included screening, preventive surgery and taking medications to prevent cancer. Researchers are also now investigating the use of dietary supplements to reduce cancer risk.

• Breast screening options include monthly breast self-exams, breast exams by a specialist every six months, and yearly mammograms. In Ontario, annual breast screening by MRI (magnetic resonance imaging) is recommended. Ovarian screening options include pelvic exams, transvaginal ultrasounds and a CA-125 blood test.



• Preventive drug therapies include taking a medication called Tamoxifen for five years. This is believed to lower the chances of developing breast cancer for women at higher risk of developing breast cancer.



• Oral contraceptives can reduce the chance of developing ovarian cancer in women with BRCA1/2 mutations (as well as in the general population).



• Preventive surgeries include preventive removal of the breast(s) (prophylactic mastectomy) and preventive removal of the ovaries (prophylactic oophorectomy). These surgeries have been shown to be very effective at reducing cancer risk, for women who choose this option.
  
  Source: The Familial Breast Cancer Research Unit, Women’s College Research Institute

  
  

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