Clinical value of multi-gene testing in distinguishing benign and malignant thyroid nodules

Abstract Background: Fine needle aspiration (FNA) has been widely applied for the preoperative diagnosis of thyroid nodules. However, it is limited mainly to testing for a single gene--BRAFV600E, whereas multi-gene testing data are extremely scarce, especially in the Asian population. This study aimed to explore the clinical value of multi-gene testing in the differential diagnosis of benign and malignant thyroid nodules based on The Bethesda System for Reporting Thyroid Cytopathology (BSRTC). Methods: A total of 615 thyroid nodules underwent ultrasound-guided fine-needle aspiration cytology (FNAC) were collected from Sir Run Run Shaw Hospital, Zhejiang University School of Medicine. The next-generation sequencing (NGS) platform was applied for multi-gene testing. A panel of well recognized commonly mutated genes in thyroid cancer were analyzed, including BRAFV600E, KRAS, NRAS, HRAS, TERT, TP53, PAX8/PPARγ, RET/PTC1 and RET/PTC3. Results: Gene mutations were identified in 324 nodules (52.7%), BRAFV600Ewas the driver gene with the highest alteration frequency (233/324, 79.1%), followed by RAS (77/324, 23.8%). The overall malignancy rate of gene mutations was 89.7% in our cohort, of which the lymph node metastasis rate was 45.3%. The combination of multi-gene testing and cytology resulted in 89.3% sensitivity, 95.2% specificity, 98.9% positive predictive value, 64.5% negative predictive value and 83.1% accuracy, which were significantly higher than those from mere cytology (sensitivity 68.6%, specificity 87.5%, positive predictive value 95.9%, negative predictive value 39.8%, accuracy 72.7%). Conclusions: Multi-gene testing could greatly increase the detection rate of malignant thyroid nodules and protect patients with benign nodules from unnecessary surgeries. Multi-gene testing provides a valuable reference for individualized preoperative decision-making, which may serve as a crucial method for postoperative treatment and prognosis assessment.