A new study by Haggi Mazeh, Iddo Ben-Dov and colleagues has identified 19 microRNAs (miRNAs) that could be used in a diagnostic panel to differentiate benign from malignant thyroid nodules with indeterminate cytology.

Fine needle aspiration biopsy is the current gold standard for the diagnosis of malignant thyroid nodules. However, 10–40% of patients who undergo this procedure have indeterminate results, meaning that molecular testing is then needed to determine the diagnosis. The currently available commercial tests are used to either rule out malignancy or to rule in malignancy, but no test can do both with high accuracy. Previous studies showed that miRNAs could be used as biomarkers to characterize thyroid nodules, leading the authors to try to identify an appropriate set of miRNAs for a diagnostic panel.

The researchers used next-generation sequencing to characterize the miRNA expression profiles of malignant (79) and benign (195) thyroid nodules. Of the 279 identified miRNAs, 19 were selected for the diagnostic panel as they showed the highest differential expression levels in malignant nodules compared with benign nodules. “Some of these miRNAs promote thyroid cancer proliferation, migration and invasion, while others inhibit proliferation of thyroid cancer cells and induce apoptosis,” explains Mazeh.

Finally, the authors tested the performance of the diagnostic panel on a set of validation samples (22 malignant and 13 benign nodules). The panel had a sensitivity, specificity, negative predictive value, positive predictive value and overall accuracy score of 91%, 100%, 87%, 100% and 94%, respectively. The overall accuracy of the panel is potentially higher than commercially available tests.

The authors are now considering performing a follow-up clinical trial to prospectively test the panel on patients.