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FDA Approves Test to Predict Breast Cancer Recurrence (dateline March 29, 2007)

The U.S. Food and Drug Administration (FDA) recently approved a test to predict the likelihood that breast cancer will return five to 10 years after the initial diagnosis. MammaPrint, made by a Netherlands-based company, is the first FDA-approved test to use molecular technology to predict whether an existing cancer will spread to other parts of the body. However, the FDA cautions that the test is more accurate at predicting which women will not experience a breast cancer recurrence rather than which women will.

"Clearance of the MammaPrint test marks a step forward in the initiative to bring molecular-based medicine into current practice," said Andrew C. von Eschenbach, M.D., Commissioner of Food and Drugs, in an FDA news release. "MammaPrint results will provide patients and physicians with more information about the prospects for the outcome of the disease. This information will support treatment decisions."

Researchers know that the return of cancer is occurs in part from the activation and suppression of certain genes in the tumor. Tests such as the MammaPrint can measure the activity of these genes and help physicians better predict the likelihood that the cancer will return in their patients.

According to Agendia, the Netherlands-based maker of the MammaPrint test, the test is a "DNA micro array-based in vitro diagnostic laboratory service that measures the activity of 70 genes, providing information about the likelihood of tumor recurrence. The MammaPrint test measures the level of expression of each of these genes in a sample of a woman's surgically-removed breast cancer tumor and then uses a specific formula or algorithm to produce a score that determines whether the patient is deemed low risk or high risk for spread of the cancer to another site. The result may help a doctor in planning appropriate follow-up for a patient when used with other clinical information and laboratory tests."

Because of the rise in microarrays and other diagnostic techniques in recent years, the use of such tests is increasing. This prompted the FDA to perform a careful examination of the benefits and risks of the MammaPrint test prior to its approval.

According to the FDA, the MammaPrint test is accurate at predicting that a woman is at high risk of having her cancer return in five years about 25% of the time. The test appears to be more accurate in predicting which women will not experience a breast cancer recurrence. According to the FDA, the test was 95% at predicting which women were at low risk of a recurrence within five years.

MammaPrint is currently sold in Europe, but it is unclear when the test will become available in the United States. The American Cancer Society estimates that about 178,480 women will be diagnosed with breast cancer in the United States this year and over 40,000 women will die from the disease.

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