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2007-9-3 13:35:43 |
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A new genetic test that is able to predict if a woman is at risk for a breast cancer relapse in future received approval from the Food and Drug Administration yesterday. This is the first ever prognostic genetic test to receive approval from the FDA. Genetic diagnostics is a relatively new and emerging technology in the medical field and promises to revolutionize the way diagnosis and prognosis is made. Breast cancer is the leading cause of cancer deaths in the United States. The American Caner Society estimates that 178,480 new cases of invasive breast cancer will be diagnosed in the country in 2007. Around 40,000 women are expected to succumb to the condition. The chances of relapse are great especially if the initial cancer diagnosis is made at a young age. Therefore a test to predict the risk of relapse can be of great use to doctors who can decide if the woman needs chemotherapy or not. Traditionally early diagnosis seems to preclude the need for drastic chemotherapy, but the risk of recurrence usually forces doctors to recommend additional treatment. However the new test called MammaPrint, aims to reduce the burden on doctors by predicting if the woman has a relapse risk. Genetic tests can also help identify patients who need aggressive chemotherapy to prevent breast cancer relapse. MammaPrint is also the first test to undergo a formal review process from any regulatory body. MammaPrint is produced by a Netherlands-based company called Agendia. It is already available throughout Europe since 2004. The company says that it has already performed about 5,000 tests for about $3,000 per test. "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. "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." Agendia's test is based on 70 genes, which are the most likely predictors of a breast cancer relapse. The MammaPrint test works by determining the level of activity of these genes in surgically removed breast tumors. Thereafter the test uses an algorithm to score the activity of the genes to determine if the chance of cancer recurrence is low or high. This result acts as a guide to help doctors plan additional follow-up treatments. But the genetic testing is not accurate in predicting the odds of breast cancer recurrence, critics say. Among those who are deemed to be at the high risk of recurrence, 23 percent would have the disease coming back. Conversely among those who are considered to be at a low risk of recurrence, 95 % will not have recurrence. The prediction of breast cancer recurrence risk at ten years is similar. Among women at high risk for recurrence, 29 percent will recur where among women at low risk for recurrence, 90 percent will not recur. Patricia Ganz, a breast cancer specialist at the University of California noted in the journal Nature that almost 50 percent of breast cancers in premenopausal women are estrogen-insensitive, thus undermining the veracity of Oncotype DX. However with MammaPrint this is not the case as the test can be used for both types of tumors. The FDA is due to hold a public meeting to draft guidance on these types of genetic tests. Dr. Steven Gutman, director of the FDA's Office of In Vitro Diagnostic Device Evaluation and Safety in the Center for Devices, admitted that there were certain shortcomings with MammaPrint. "This information has to be used very carefully by physicians in the context of what they know about the history of the patient, the diagnostic options and the treatment options," Gutman said. "This is a complex test that requires use by people who know their business." Dr. Len Lichtenfeld, the deputy chief medical officer at the American Cancer Society, felt that the test was no better than other available on the market. However the FDA approval was a plus point. "The goal of that process is to do a test that will tell us, 'Yes, you need adjuvant therapy or, no, you don't,' and say it with 99.9 percent accuracy. We are not there yet," he added. |
