Prediction of radioactive iodine remnant ablation failure in patients with differentiated thyroid cancer: A cohort study of 740 patients

Abstract Background The purpose of this study was to detect parameters that could serve as predictors of radioactive iodine (I‐131) ablation failure in patients with low‐risk and intermediate‐risk differentiated thyroid carcinoma (DTC). Methods Our cohort study included 740 patients with DTC who received postoperative I‐131 remnant ablation. Anthropometric, biochemical, and pathohistological parameters were analyzed and correlated with ablation outcome using multivariable logistic regression models. Results Treatment failure rates were higher in patients <53 years, with N1a classification, and lymph node capsular invasion. In patients with N1a disease, thyroglobulin (Tg) > 2.4 ng/mL predicted treatment failure with 93.8% sensitivity and 52.5% specificity, and in patients with N1b disease, Tg > 14.9 ng/mL with 77.8% sensitivity and 92.9% specificity. I‐131 activity was not associated with treatment outcome. Conclusion Patients < 53 years old, with higher Tg levels, N1a classification, and lymph node capsular invasion have a higher risk of ablation failure. Stimulated Tg is an excellent predictor of treatment failure in patients with N1 disease. © 2016 Wiley Periodicals, Inc. Head Neck 39: 109–115, 2017