New Genetic Test for Breast Cancer Approved by the FDA

A new medical test called MammaPrint was approved today by the FDA. MammaPrint predicts the likelihood that early-stage breast cancer will recur or spread.

The test is made by Agendia, an Amsterdam company, and it has been available in Europe since 2005. Today's FDA approval opens the way to the test becoming available in the United States, although that won't happen immediately.

Cancer recurrence depends, in part, on the activation of certain genes, and the MammaPrint tests works by measuring 70 genetic markers in a sample from a breast cancer tumor. The data is then analyzed by computer. Testing for 70 genetic markers is what distinguishes MammaPrint from other genetic tests, already on the market in the U.S., which measure only a single signal.

While the test is a significant advance, it is far from perfect, said Dr. Steven Gutman, director of the FDA's Office of In Vitro Diagnostic Device Evaluation, who spoke at a press conference. He said the test is better at predicting who won't relapse (for which the test is 90 - 95% accurate) rather than who will (for which the test is only 23 - 29% accurate).

Dr. Gutman also cautioned that the test must be interpreted by experienced oncologists and should be used in conjunction with other medical information, such as the patient's medical history and other test results. Reuters quotes Dr. Gutman as saying that "it's better than having no information at all. It does provide a risk profile for patients," and he said it was an important step towards personalizing treatment for individual patients.

According to the Associated Press, out of the more than 178,000 women who will be diagnosed with breast cancer this year in the United States, more than 100,000 of them will have "early stage tumors with a remarkably good prognosis: They're small, they haven't yet spread to the lymph nodes, and they're sensitive to hormones."

The vast majority of these women with a good prognosis would not need chemotherapy to survive -- only surgery, radiation, and hormone treatment. But current guidelines do recommend chemotherapy for all, in order to ensure that the women who do need the more aggressive treatment to prevent a recurrence will get it, even though the percentage of women who would benefit from the chemotherapy is very small -- only two or three per 100.

Therefore, a test such as MammaPrint which predicts the risk of recurrence can identify the women who are the least likely to need chemotherapy. Those women can then decide if they want to take a chance and skip the chemotherapy treatment and its accompanying discomforts.

FDA approves new breast cancer test, by Lauran Neergaard, Feb. 6, 2007, Associated Press

FDA Okays Gene Test to Predict Breast Cancer Recurrence, by Peggy Peck, Feb. 6, 2007, MedPage Today, medpagetoday.com

UPDATE 1-U.S. OKs test to predict breast cancer return, by Lisa Richwine, Feb. 6, 2007, Reuters