Women's Health: A New Gauge of Breast-Cancer Risk
Chemotherapy can be lifesaving, but it's also unpleasant and carries long-term health risks. That's why doctors would love to be able to accurately gauge the chance that cancer will return, so they could treat the people who needed to be treated and let the rest forgo the hazards of chemo. The Food and Drug Administration has approved an additional tool in the case of breast cancer to move that scenario closer to reality: On Tuesday it OK'd the MammaPrint, a test that looks at 70 genes to calculate the odds that women in the early stages of breast cancer will experience a recurrence of the disease.
The new test isn't the only one of its kind. Another test, Oncotype DX, also analyzes genes to predict the risk of breast cancer recurrence. But the MammaPrint, intended for women whose cancer hasn't spread to nearby lymph nodes, was the first of this kind of test to get FDA approval. That thumbs up is not currently required, but its manufacturer, the Dutch company Agendia, wanted the stamp of approval from the FDA. The FDA is currently weighing how it might regulate the performance of these tests and will hold hearings on the topic on Thursday.
This technology, while promising, isn't likely to change practice yet for most breast cancer patients and their doctors. The MammaPrint isn't perfect; it produces both false positives and false negatives. Over five years, just 23 percent of the women it predicts to be at high risk will actually have their cancer return. More encouraging: 95 percent of women it classifies as low risk will not see a recurrence. That's better than having no information at all, but "you can't go all the way to the bank with this," said Steven Gutman, director of the office of in vitro diagnostic device evaluation at the FDA, in a conference call with reporters.
Oncologists and surgeons currently use other tools to estimate the odds of recurrence, including whether cancer has spread to nearby lymph nodes and the size of the original tumor. These new gene tests are a more formal and accurate predictor, says Monica Morrow, head of surgical oncology at the Fox Chase Cancer Center in Philadelphia. But will women at low risk of the disease want to take even a small chance that their disease will come back?
Len Lichtenfeld, deputy chief medical officer of the American Cancer Society, says cases where doctors use these tests to determine a woman's treatment are now "the exception, rather than the rule." But he hails this and similar tests as a good first step to the ultimate goal of personalized treatment based on the genetic makeup of a woman's tumor.