STATISTICAL COMPARISON OF AFIRMA GSC AND AFIRMA GEC OUTCOMES IN A COMMUNITY ENDOCRINE SURGICAL PRACTICE: EARLY FINDINGS

Abstract Objective: The Veracyte Afirma Gene Expression Classifier (GEC) has been the most widely used negative predictive value molecular classifier for indeterminate cytology thyroid nodule aspirates (FNA's) since 1/2011. To improve specificity and further reduce unnecessary thyroid surgeries, a second generation assay (Afirma GSC) was released for clinical use in 8/2017. We report 11 months of clinical outcomes experience with the GSC and compare them to our 6.5 year experience with the GEC. Methods: We searched our practice registry for FNA's with Afirma results from 1/2011-6/2018. GEC vs GSC results were compared overall, in oncocytic and non-oncocytic aspirates and by pathologic outcomes. Results: GSC identified less indeterminate cytology nodules as suspicious (38.8%–54/139) when compared to GEC (58.4%–281/481). There was a decrease of in the percentage of oncocytic FNA subjects classified as suspicious in the GSC group, with 86 out of 104 oncocytic indeterminates (82.7%) classified as suspicious b...