New Test Could Predict Recurrence of Breast Cancer

Feb. 7, 2007 — -- The government has recently approved a new genetic test for women with breast cancer.

The test helps measure the risk of a relapse after treatment, and it could help a woman with a lower risk skip more aggressive treatments like chemotherapy.

MammaPrint, which already sells in Europe, will allow doctors to test the genetic makeup of a tumor. Experts say this could help determine what kind of treatment a cancer patient may need.

More than 178,000 U.S. women will be diagnosed with breast cancer this year, and the vast majority of those women would survive with surgery, radiation and hormone treatment.

Current guidelines also recommend chemotherapy for most, to catch the few patients -- two or three out of every 100 -- who need more aggressive help to try to prevent a recurrence years later.

Although previous tests based on anatomy, hormones and lymph nodes have been valuable, at a basic cell level breast cancers are different, according to "Good Morning America" medical contributor Dr. Tim Johnson.

"This heralds a whole new way of diagnosing breast cancer and who really needs chemotherapy," Johnson said. "This [test] profiles the genetics of the tumors … and may indicate whether chemotherapy is needed."

The test is now being studied in a clinical trial.

Current studies showed that 23 percent of breast cancer patients whom the test characterized as high risk had a recurrence of the disease, while 5 percent of the women characterized as low risk had a recurrence.

Johnson called the test "far from perfect," but as the first-approved test for this purpose, it is the "wave the of future."

"I have very little doubt that in 10 to 15 years that we're going to take tumors at the time of diagnosis, [diagnose] them genetically … [and] sort out who really needs chemo or who doesn't," Johnson said.

The test, however, has limits. It can only be used on women younger than 61 with early-stage breast cancer.

For women who had the disease years ago, it may not be useful in predicting a recurrence because a fresh tumor sample is needed, according to Johnson.