Women's genes and heritage reveal cancer risk

After reading about a research study to test genetic mutations that can increase the risk of breast cancer in Jewish women back in May 2008, Marsha Moshinsky signed up immediately. “I want to know if I, and therefore possibly my children, carry these mutated genes,” she wrote in her journal that day. “If I am a carrier, I want to face the risks head on, with as much knowledge as possible and with preventive treatment at my disposal.”

The results of that study, which tested more than 2,000 women, were published in December 2009 in the Journal of Clinical Oncology. The findings: Just over one per cent of Jewish women in Ontario carry the mutated BRCA1 or BRCA2 genes -- about four times higher than the general population. The mutated gene means carriers have an 80 per cent risk of developing breast cancer and up to a 40 per cent risk of developing ovarian cancer.

Shocked by the results
Of those who tested positive, more than half were ineligible for testing according to provincial guidelines, which are similar across the country and in the United States. To be qualified for screening, you must have a history of breast or ovarian cancer or a strong history of these diseases in your family.

“We were surprised by the lack of family history,” says lead author Kelly Metcalfe, adjunct scientist at Women’s College Research Institute. “The women getting the results were very shocked as well. There had been nobody in their family with cancer, and we don’t often observe BRCA 1 or 2 mutations in families without significant histories of breast and ovarian cancer.”

Additionally, 45 per cent of the women with a mutated gene were eligible for testing but were never referred by their physicians. “I think it’s probably because the majority of the mutations were coming from the father’s side,” Metcalfe explains. “There is this misunderstanding out there that breast cancer risk can’t be inherited through a father. That’s false. It’s just as likely to come from the father’s side as it is the mother’s side.”