Abstract 75: Prediction score for malignancy in thyroid nodule

Background: In India, prevalence of differentiated thyroid cancer (DTC) is 0.1% and incidence has increased over past decade by 55%. Aims and Objectives: To formulate a scoring system for prediction of malignancy in thyroid nodule using clinical risk factors, ultrasound and FNAC characteristics. Consecutive subjects >10 years, with palpable or ultrasound-revealed thyroid nodule who presented to outpatient department underwent ultrasonography for determination of 2017-ACR-TIRADS. All nodules >1 cm maximum diameter and those with TIRADS score of 4 or 5 with maximum diameter >5 mm underwent ultrasound-guided FNAC. All Bethesda 4, 5 and 6 nodules underwent thyroidectomy. Patients with Bethesda 3 nodules were given option of close follow up or surgery. Results: Present study found age and TSH to be significantly different between benign and malignant nodules. Hence a prediction score (Trivandrum prediction score (TiPS)) was formulated with four variables namely age, TSH, 2017 ACR TIRADS and Bethesda score, for predicting risk of malignancy in nodule. Each of the four variables were stratified and weightage points assigned. Age (in years) >40;0, <40;1. TSH (mIU/L)< 2;0, >2;1. TiPS=age score+TSH score+[TIRADS-1]+[Bethesda -2]x2. Final outcome variable was considered as the gold standard and was defined as FNAC report of Bethesda2 or all other nodules which had undergone surgery and histopathology (HPR) is available. Nodules with either Bethesda 2 report on FNAC or a benign HPR report were considered benign. HPR report of malignancy was considered malignant. 226/240 nodules included in study had final outcome variable. ROC curve was analysed for cut off value of total prediction score. Total score >6 had a sensitivity of 96.2% and specificity of 97.5% in predicting malignancy. Conclusions: Cumulative scoring system had high diagnostic accuracy for prediction of malignancy risk and can be a useful tool in clinical practice for selecting thyroid nodules for surgery, especially indeterminate nodules.