The Clinical Utility of Ultrasound and Serological Features Derived Nomogram for the Prediction of Lateral Lymph Node Metastases in Medullary Thyroid Cancer.

[OBJECTIVE] To evaluate the diagnostic value of Ultrasound (US) and serological features in detecting lateral lymph node metastasis (LLNM) in medullary thyroid carcer (MTC).

[METHODS] This study retrospectively analyzed 158 MTC patients who underwent thyroidectomy at two medical centers from February 2011 to September 2023. Preoperative US characteristics and serological features were examined, and univariate and multivariate logistic regression analyses were conducted to identify independent risk factors for LLNM, followed by developing a nomogram. The predictive performance of the nomogram was assessed using the area under the receiver operating characteristic curve (AUC), calibration curves, decision curve analysis (DCA), and clinical impact curves (CIC).

[RESULTS] Compared to non-LLNM patients, those with LLNM were significantly associated with higher preoperative levels of carcinoembryonic antigen (CEA) and calcitonin (Ctn), as well as lower thyroxine (T) levels. Additionally, preoperative LLNM suspicion on US was strongly indicative of its presence. The nomogram based on these risk factors demonstrated excellent predictive performance, achieving an AUC of 0.922, specificity of 0.806, and sensitivity of 0.932 in the training set. In the validation set, the model achieved an AUC of 0.918, specificity of 0.792, and sensitivity of 0.913. Calibration curves, DCA, and CIC confirmed the nomogram's strong predictive capability, net benefit, and clinical utility.

[CONCLUSION] Preoperative CEA, Ctn, T levels, and LLNM suspicion on US are important predictors of LLNM. The nomogram based on these factors demonstrated high predictive capability, highlighting its potential as a valuable preoperative tool for assessing LLNM risk in MTC patients.