Deaver KE, et al. - Given that the second edition Bethesda System for Reporting Thyroid Cytology estimates 6%-18% malignancy rate of category III (B3) and 10%-40% for category IV (B4) nodules, the researchers analysed malignancy rates of B3 and B4 nodules and determine clinical outcomes of Afirma Gene Expression Classifier (GEC) Benign nodules. From 2011 to 2015, a retrospective analysis of 2019 thyroid FNAs were performed at the University of Colorado, including molecular, surgical and clinical follow-up. They found that malignancy rates of B3 and B4 nodules showed year-to-year variability. Clinicians use a multi-year average of their institution's malignancy rates to optimally manage patients was suggested. Follow-up for GEC Benign cases thus far supports their indolent nature.