Endeavors magazine: Gene test guides Cancer Treatment

Gene test guides Cancer Treatment

by Jan McColm

Good news for breast cancer patients.

There are many different treatments for breast cancer, and predicting which cancer patients need which treatment isn’t easy. “Doctors already know that 10 to 30 percent of breast cancer patients will do very well almost no matter how you treat them,” says geneticist Charles Perou. Until now, there hasn’t been any way to identify these patients. So to be safe, doctors treat all patients, primarily with chemotherapy. Given the side effects associated with chemo — hair loss, nausea, and anemia, to name a few — knowing whom to treat would spare many patients unnecessary pain.

“Breast cancer is one of the cancer types where genetic tests are available in the clinic,” Perou says. But there are several different tests for breast cancer available, and each measures a different set of genes. “It was somewhat confusing to me,” he says, “as to whether all these different tests were testing different things, or whether they were all tracking the same basic biology of breast cancer.”

So Perou’s team looked at five different gene tests — including their own newly devised test — and compared their outcomes in the same set of 295 patients. Turns out four of the five gene tests were in strong agreement. It doesn’t matter which of those four tests you administer, Perou says, you’ll get the same outcome.

That’s good news for the breast cancer patients who do well no matter the treatment. “If the test predicts their outcome is the same if you give them chemotherapy or not, then don’t give it to them, because it’s expensive, toxic, and they’ll get no benefit,” Perou says.

Perou’s new test is also good news for other patients. “Because our test is based on the biology of the tumor, it includes the presence or absence of specific drug targets,” he says. That means that doctors now have an extra tool in deciding which of the many available treatments patients should get.

Charles Perou is an assistant professor of genetics at Carolina. His study was published in August 10, 2006 issue of the New England Journal of Medicine.