Development and validation of a nomogram to predict failure of initial radioactive iodine therapy in differentiated thyroid cancer: a retrospective cohort study.

Given the scarcity of studies predicting iodine-131 treatment failure based on clinicopathological factors, this study aimed to determine whether clinicopathological features can predict iodine-131 treatment failure in differentiated thyroid carcinoma (DTC) patients. A total of 182 patients were analyzed, including 114 with favorable outcomes and 68 with resistance or poor outcomes. Patients were split into a training set (122 patients) and a validation set (60 patients). Logistic regression identified the number of lateral neck lymph node metastases (P = 0.001) and pre-radioactive iodine therapy serum thyroglobulin levels (P = 0.001) as independent predictors of treatment failure. The predictive model, visualized via a nomogram, achieved area under curves (AUCs) of 0.838 (95% CI, 0.759-0.917) and 0.766 (95% CI, 0.626-0.905) in the training and validation sets, respectively. Calibration curves showed good agreement between predicted and observed outcomes, and decision curve analysis confirmed the model's clinical utility. Subgroup analyses yielded AUCs of 0.777 (95% CI, 0.648-0.906), 0.745 (95% CI, 0.646-0.843), 0.734 (95% CI, 0.649-0.820), and 0.911 (95% CI, 0.769-0.999) for male, female, age < 55, and age ≥ 55 groups, respectively. This model effectively predicts iodine-131 treatment failure risk in DTC patients, providing valuable information for clinical decision-making.