TRACKING A KILLER

Health authorities in Ontario, Canada have embarked upon a massive saliva test to determine breast cancer. Thousands of women are queuing up.

About 70 per cent of women who carry a mutated version of the BRCA1 or BRCA2 genes will develop breast cancer by age 70, according to Dr. Steven Narod, who heads the breast cancer research unit at Women's College Hospital in Toronto. The mutation often runs in Jewish families, but the provinces currently have restrictions on funding for genetic testing.

Since an accurate saliva test would be cheaper and painless compared with blood tests, Narod hopes provincial health plans might be expanded to screen more women if the project succeeds. "The ability to do a test from a spit rather than from a blood test really opens up this field to women who traditionally had not been eligible or had not had access to the services," Narod said. Women who lined up to give saliva at the Toronto hospital this week said they dreaded the possibility of finding out they had the mutation, but also wanted to do everything they could to prevent breast cancer.

Dr. Narod's research program is divided into four research themes:

The second phase will focus specifically on preventive oophorectomy, the removal of one or both ovaries. Because women who carry a mutation of BRCA1 have a lifetime risk of approximately 40 percent of developing ovarian cancer, prevention of the disease in these women is critically important. Current prevention techniques include oral contraceptives, tubal ligation and prophylactic oophorectomy, but the latter carries with it some impairment of quality of life. The purpose of Dr. Narod's study is to evaluate the impact of prophylactic surgical oophorectomy on the lives of 300 women over a five-year period. In addition to assessing quality of life issues, the study will measure the level of risk reduction of ovarian and peritoneal cancer, and establish whether the risk reduction is related to the age of the surgery, the surgical procedure, previous use of oral contraceptives and/or tubal ligation.

In his third phase of research, Dr. Narod will seek to identify the relationship of several treatment factors - including surgery, radiotherapy, chemotherapy and the drug tamoxifen - to selected outcomes in women with BRCA1 or BRCA2 mutations. Finally, Dr. Narod will calculate the risk of developing breast cancer for non-carriers, with regard to age, family history and the degree of relationship from affected women.

In 2008, an estimated 22,400 women will be diagnosed with breast cancer and 5,300 will die of it, according to the Canadian Cancer Society.

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