Abstract
BACKGROUND: Distant metastases are the leading cause of death for patients with differentiated thyroid cancer (DTC), and surgery and radioactive iodine (RAI) therapy are effective treatments for them. However, there remains a large proportion of patients with poor prognoses, and there exists no consensus on whether systemic chemotherapy or beam radiation should be administrated to improve their prognoses. METHOD: The clinicopathology information of patients with metastatic DTC (mDTC) was retrospectively collected and analyzed. A nomogram was created to predict their prognosis and divided patients into high- and low-risk groups, and the external validation was performed. RESULTS: The Cox regression showed that sex, age, metastatic sites, surgery, and radiotherapy were independent influencing factors affecting OS. Fine-gray competing risk analysis showed that age, T-stage, N-stage, metastatic sites, and radiotherapy were independent risk factors for TCSD. The nomogram we constructed proved to be effective and robust with high efficiency, with C-indexes of 0.785 (95% CI = 0.752-0.813) and 0.794 (95%CI = 0.766-0.831) on the train and test sets, respectively. mDTC patients were further classified into high- and low-risk groups based on the prediction of nomogram, those in the high-risk group had significantly worse OS and higher TCSD than those in the low-risk group (P < 0.001), and chemotherapy significantly improved OS and reduced TCSD for patients in the high-risk group, whereas local beam radiation did not provide any survival benefit. In the external validation dataset, the 1-, 3-, and 5-year AUC values of the model ranged from 0.833 to 0.873, which further proved the efficiency of our model. CONCLUSION: This study developed an accurate prognostic model for patients with mDTC, which may be applicable in future clinical practice for prognosis and death prediction. For high-risk patients, as predicted by nomogram, systemic chemotherapy was the recommended therapy option for them.