New Test May Spare the Need for Surgery to Diagnose Thyroid Cancer

July 2012, Vol 3, No 5

Diagnostic surgery is often used to evaluate the 15% to 30% of thyroid nodules that cannot be judged benign or malignant by the use of fine-needle aspiration (FNA). However, such surgery is associated with a 2% to 10% risk of serious complications. A new geneexpression test may soon be used for the diagnosis of such nodules, which could reduce the use of diagnostic surgery in this population (Alexander EK, et al. N Engl J Med. Epub 2012 Jun 25).

This prospective, double-blind study involved 4812 FNA samples from 3789 patients over a 19-month period. Of these samples, 577 cytologically indeterminate nodules were further examined to determine their clinical significance. The gene-expression test was performed on the tissue from the patients who also had the surgery and therefore had histopathological review results to serve as a reference standard.

Of 265 nodules that met the inclusion criteria based on a blinded histopathological review, 85 were malignant. The use of the geneexpression test identified 78 of the 85 malignant nodules, yielding a sensitivity of 92% (95% confidence interval, 84-97). The negative predictive values for “atypia (or follicular lesion) of undetermined clinical significance” and “follicular neoplasm or lesion suspicious for follicular neoplasm” were 95% and 94%, respectively. These values suggest that for aspirates with either of these subtypes and a benign gene-expression test result, the probability of malignancy is as low as that for nodules shown to be benign with FNA.

The researchers suggested that routine use of the gene-expression test may potentially offer cost-savings by reducing unnecessary surgery.

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