Outcomes of Bethesda categories III III and IV IV thyroid nodules over 5?years and performance of the Afirma gene expression classifier: A single‐institution study

摘要

Summary Objective 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; however, reported malignancy rates have considerable variability among institutions. Use of molecular classifiers (including Afirma Gene Expression Classifier, GEC ) can be utilized in management of thyroid nodules. Our objective was to analyse malignancy rates of B3 and B4 nodules and determine clinical outcomes of GEC Benign nodules. Methods A retrospective analysis of 2019 thyroid FNA s was performed at the University of Colorado from 2011 to 2015, including molecular, surgical and clinical follow‐up. Results Of 2019 FNA s analysed, 231 (11.4%) were diagnosed as B3 and 80 (4.0%) as B4. GEC was obtained in 54.1% of B3 cases, with nearly half (48.8%) having a Benign result. Surgery was performed in 40.7% B3 cases with a 24.5% malignancy rate, ranging 8%‐38% by year. In the B4 group, 52.5% underwent molecular testing with 28.6% as GEC Benign. About 68.8% of B4 cases underwent surgery with a 20% malignancy rate, ranging 0%‐42% by year. Seventy‐three GEC Benign cases were reviewed: 5 (6.8%) underwent surgery, with none demonstrating malignancy in the target nodule. Size remained stable for most GEC Benign nodules: 75.9% (B3) and 71.4% (B4) with no malignancy on repeat FNA . Conclusions Our 5‐year review demonstrated that malignancy rates of B3 and B4 nodules showed year‐to‐year variability. We suggest that clinicians use a multi‐year average of their institution's malignancy rates to optimally manage patients. Follow‐up for GEC Benign cases thus far supports their indolent nature.