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Volume 17, Number 5
May 2011

What your genes say

Greg Zaric’s research analyses the cost-effectiveness of genetic testing in health care

If you’re a woman with an abnormal BRCA1 gene, you have a higher risk of developing breast or ovarian cancer. If you’re a carrier of the “mutant type KRAS” gene, you’ll get no benefit from cetuximab, a drug that’s used to treat colorectal cancer.

Genetic tests are being used more and more in the detection and treatment of cancer. As these tests become commercially available they raise an important question for health care policy: under what circumstances should they become publicly funded?

With a health system that’s already overburdened, a key issue is whether the extra expense of a genetic test will result in future savings. Ivey professor Greg Zaric, Canada Research Chair in Health Care Management Science, focuses his research on issues of cost effectiveness in the health care industry. Genetic testing comes with a trade off, he says. “Some of these tests are quite expensive, and they’re not always accurate. But on the other hand if they do work, we can direct patients into optimal treatment, which yields clinical benefits for the patients and may save costs in the long run.”

In one of his recent studies, Zaric and a PhD student looked at the Oncotype DX® breast cancer assay, a diagnostic test that shows the likelihood of a woman with breast cancer having a recurrence within the next 10 years. Based on the expression of 21 genes, the test comes up with a score that classifies a woman as high, medium, or low risk. “The idea behind the test is that women at high risk would want to undergo chemotherapy,” says Zaric. “On the other hand, women at low risk would not likely benefit from chemotherapy, which has many unpleasant side effects and is expensive.”

The test is not publicly funded in Ontario, although many feel it should be. In his study Zaric examined the cost-effectiveness of making the test available to everyone, as compared to continuing to use accepted clinical practice guidelines for treating breast cancer. The analysis involved a number of components, including the extra cost of the test, its clinical accuracy, and the change in costs associated with changes in clinical outcomes.

In Zaric’s study he divided women into a number of categories, such as lymph node positive and lymph node negative, and premenopausal and postmenopausal. He found that in some categories the test was very cost-effective and in others borderline.  “Although we’re still finalizing our work, preliminary results suggest that overall it would be cost-effective to make use of the test,” he says.

Zaric recently received funding from the Canadian Institutes of Health Research to study genetic testing in “cancers of unknown primary.” A cancerous tumour originates in one part of the body, but sometimes spreads to another. Cancer of unknown primary is diagnosed when cancer is found, but the originating location in the body cannot be determined. This might be because the original tumour has disappeared, or is too small to be identified. It’s clinically important to know the primary source because different treatments are used for different cancers.

In the last five years a number of genetic tests to determine cancer of unknown primary have either come onto the market or are in some stage of development. None of the tests are funded, and the purpose of Zaric’s study is to determine their cost implications. “We’re developing some models that allow us to capture the trade-offs involved in the expense of these tests, their imperfect accuracy, and the possibility for improved clinical outcomes,” he says. “Our results will tell us whether these tests are economically attractive compared to the way we now spend our money in the healthcare system.”

Zaric first learned about genetic testing in cancers of unknown primary from a newspaper article that raised arguments about whether these tests should be publicly funded.  “When I saw the numbers being thrown around in the article, I felt there was a need and an opportunity to do an analysis to clarify the debate.”

Health policy makers recognize the value of Management Science as an important tool in the decision to make public funding available for tests and drugs. “The regulators who make these decisions are quite sophisticated in their understanding of mathematical and economic models and the kinds of tools that management scientists use to do this,” says Zaric.

Zaric recognizes that economic evaluation is not the sole determinant in the decision to provide public funding.  “There are other factors in play,” he says. “But health economics represents a way of bundling together three pieces of information - cost, survival, and quality of life - which are important under anybody’s way of thinking.”

Professor Zaric's Homepage