European experience with the Afirma Gene Expression Classifier for indeterminate thyroid nodules: A clinical utility study in the Netherlands

BackgroundThe Gene Expression Classifier (GEC) and Genomic Sequencing Classifier (GSC) were developed to improve risk stratification of indeterminate nodules. Our aim was to assess the clinical utility in a European population with restrictive diagnostic workup. MethodsClinical utility of the GEC was assessed in a prospective multicenter cohort of 68 indeterminate nodules. Diagnostic surgical rates for Bethesda III and IV nodules were compared to a historical cohort of 171 indeterminate nodules. Samples were post hoc tested with the GSC. ResultsThe GEC classified 26% as benign. Surgical rates between the prospective and historical cohort did not differ (72.1% vs. 76.6%). The GSC classified 59% as benign, but misclassified six malignant lesions as benign. ConclusionImplementation of GEC in management of indeterminate nodules in a European country with restrictive diagnostic workup is currently not supported, especially in oncocytic nodules. Prospective studies with the GSC in European countries are needed to determine the clinical utility.

Automated summary

This study evaluated the clinical utility of the Gene Expression Classifier (GEC) and Genomic Sequencing Classifier (GSC) in a European population. The results showed that the GEC was not clinically useful in identifying benign lesions in indeterminate nodules, especially in oncocytic nodules. The GSC misclassified some malignant lesions as benign.