Alexander and colleagues reported the results of a prospective, multicenter study of 3789 patients who underwent fine-needle aspiration (FNA) of thyroid nodules (New England Journal of Medicine, August 23, 2012). The goal of FNA is to identify patients who have thyroid cancer and require thyroidectomy. Unfortunately FNA is not always diagnostic, and some nodules are pathologically indeterminate, meaning that cancer can not be excluded. Currently many of these patients have thyroid surgery, though the majority of patients with indeterminate results on FNA do not have thyroid cancer. Alexander et al. report that a molecular test performed on the FNA sample, a gene-expression classifier, can identify patients with true cancers (78 of 85 malignant nodules were identified), and exclude malignancy as a diagnosis in 85-95% of cases. In an accompanying editorial in NEJM, Dr. J. Larry Jameson writes that use of the molecular test could result in a reduction in up to 1/3 of all thyroid surgeries, or 25,000 surgeries a year, in the United States . Gene expression classifiers measure the expression of multiple genes and use a formula to calculate a score that can be predict whether a nodule is benign or malignant. The study was supported by research grants from Veracyte, the maker of the gene expression classifier.
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