Genetic cancer risks

OLGA LIVSHIN

In medical lingo, the term “founder group” means a large, self-contained community, which for various geographical or politico-cultural reasons has existed relatively intact for generations. Ashkenazi Jews form one such group.

Genetic research shows that, in this particular group, three genetic mutations in the genes BRCA1 and BRCA2 occur more often than in the general population. These mutations effectively increase the risk of breast and ovarian cancers among women of Ashkenazi Jewish descent.

The genes were discovered 15 years ago by Dr. Steven Narod of the Women’s College in Toronto. Since then, numerous studies on these genes and their mutations have been conducted. The outcomes shed light on the following statistics.

• Of the women who didn’t inherit the BRCA1 or BRCA2 mutations, about 12 percent might develop breast cancer during their lifetimes. The risk of developing breast cancer among the women with the mutations is five times higher – about 60 percent.

• The estimated lifetime risk for ovarian cancer among women in the general population is about 1.4 percent, whereas women who carry a BRCA1 or BRCA2 mutation have a 15 to 40 percent risk of being diagnosed with ovarian cancer.

• The most unfortunate result of these studies concerns the Ashkenazi Jewish population: among women belonging to it, anywhere from one to three percent carries a harmful BRCA1 or BRCA2 mutation. The number of carriers in the general population is five times lower.

Ashkenazi Jews’ tendency for these mutations is well known in the medical community, and genetic testing is available in Canada. In British Columbia, the B.C. Cancer Agency has administered the Hereditary Cancer Program since 1996.

Jenna Scott, a genetic counselor and clinical coordinator of the initiative, told the Independent that the program provides genetic testing and counseling services throughout the province.

“Imagine a gene as a phone book. Whenever there is a spelling mistake, it means a mutation has occurred,” Scott explained. “It’s hard and expensive to test for one spelling mistake in a phone book, unless we know the exact place and the specific mistake we’re looking for. That’s what the testing for BRCA1 or BRCA2 mutation is like – we know how and where to look for them.”

According to Scott, it is not only those mutations that factor in cancer development. Family history, especially first-degree relatives diagnosed with cancer, is important too, as is the environment. “Knowing your family history is a start,” she said. “If you have concerns in that direction, talk to your family physician. If you meet the criteria for testing, your physician will refer you to us.”

Higher risk when an individual carries the cancer mutation doesn’t mean that she or he will inevitably develop cancer, although the chances of being diagnosed, and often at a younger age, increase dramatically. This is where counseling can help.

“Our goal is to reduce mortality and morbidity,” Scott said. “An earlier start of cancer screening – mammograms – might be recommended. Some women might opt for preventive surgery – double mastectomy, oophorectomy [removal of the ovaries] or both – to remove the organs at risk.”

But surgery is a trauma, physical as well as mental, and quality of life is genetic counselor’s main concern. “We offer information and provide the options to explore, so people can make informed decisions,” Scott said.

Of course, not every small town in British Columbia has a cancer clinic, but the counselors travel regularly. They offer video conferences to patients living in rural and remote regions. “It reduces the level of stress for our patients,” Scott said. “Some people hate coming to the ‘big city.’ They feel more comfortable talking to a counselor from the comforts of their own community, surrounded by family support.”

Despite the common adage “knowledge is power,” not everyone chooses to undergo genetic testing and counseling, even if they have a strong family history of the disease and qualify under the Hereditary Cancer Program’s guidelines. Some people are afraid to find out, while others, who want to know, might not meet the criteria of the program.

Those criteria are subject to controversy. Recently, Narod and his partner, Dr. Kelly Metcalfe, and their team, conducted a study among Ashkenazi Jewish women in the Toronto area to determine if the current guidelines for genetic testing for the BRCA1 and BRCA2 mutations among this particular founder group should be changed. Their report was published in the January 2010 Journal of Clinical Oncology. Of 2,080 women enrolled in the study, 22 were mutation carriers, but only 10 of the 22 women (45 percent) met the current criteria for testing. The authors suggest that it might be prudent to make the guidelines for testing more flexible, especially for those at a higher risk, like Ashkenazi Jews. The study has been extended for one more year.

Olga Livshin is a Vancouver freelance writer. She’s available for contract work. Contact her at [email protected].

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