miércoles, 11 de julio de 2012

Test May Reduce the Need for Surgery to Diagnose Thyroid Cancer ▲ NCI Cancer Bulletin for July 10, 2012 - National Cancer Institute

NCI Cancer Bulletin for July 10, 2012 - National Cancer Institute


Test May Reduce the Need for Surgery to Diagnose Thyroid Cancer

A new test may spare some patients with suspicious thyroid nodules from diagnostic surgery. Researchers analyzed thyroid nodule samples collected via fine-needle aspiration (FNA) for the expression of a panel of 167 genes and found that the test accurately identified whether nodules were cancerous. Their results were published June 25 in the New England Journal of Medicine.
About 15 to 30 percent of patients undergoing FNA for suspicious thyroid nodules have indeterminate findings on standard cytology tests—that is, the tests show cellular changes that indicate a possible cancer but the findings are inconclusive. Although the majority of those with inconclusive cytology results have a benign condition, most have thyroid surgery to determine whether cancer is present.
Several researchers said the test has the potential to change clinical practice by eliminating or delaying the need for such surgery in some patients.
The researchers collected more than 4,800 aspirate samples from nearly 3,800 patients treated at 49 academic centers and community hospitals over a 19-month period. Of these, they analyzed indeterminate FNA samples from 265 nodules for which surgical samples were also available. The FNA samples were analyzed using the 167-gene panel that the researchers had developed based on earlier research.
Overall, when the results from the gene expression test were compared with diagnostic results from thyroid samples removed during surgery, the test correctly identified 92 percent of the malignant samples and 93 percent of the benign samples. But about half of the samples that the gene expression test identified as suspicious—not clearly malignant or clearly benign—were actually benign on surgical analysis.
For patients with indeterminate cytology results, the gene expression test "can be useful in making important [patient] management decisions, such as recommending watchful waiting in lieu of diagnostic surgery," wrote lead author Dr. Erik Alexander of Brigham and Women's Hospital and his colleagues.
Dr. Ann Gramza of NCI's Center for Cancer Research agreed. But she cautioned that "a negative result should not dismiss a patient from further follow-up surveillance of the nodule."
"The risk…is that 5 to 10 percent of nodules classified as benign...are likely to be malignant [false negatives], particularly those that are cytologically indeterminate but suggestive of cancer," wrote Dr. J. Larry Jameson of the University of Pennsylvania in an accompanying editorial. In such patients, he explained, "it might be reasonable" to do another FNA biopsy or perform a diagnostic surgical procedure.
One recent study, Dr. Jameson noted, suggested that the reduction in surgeries that could result from its use—about 25,000 fewer operations per year—"could result in substantial cost savings," even with the added cost of the test.

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