An ultrasound-based nomogram for predicting central lymph node metastasis in papillary thyroid microcarcinoma

Performing prophylactic central lymph node dissection for papillary thyroid microcarcinoma (PTMC) patients with clinically negative lymph node metastasis remains controversial - not all patients with PTMC are suitable for active surveillance. Therefore, we aimed to establish a nomogram based on ultrasound features for predicting CLNM in PTMC. This retrospective study included 636 patients with PTMC, in which the CLNM status was pathologically confirmed. Univariate and multivariate regression analyses were conducted to screen for risk factors associated with CLNM. Then, a CLNM prediction model was established, receiver operating characteristic, calibration, and decision curve analyses were used to assess the model's performance. Five variables, including age, sex, combined CLNM status, tumor size, and capsule invasion, were included in the nomogram. The values of the area under the receiver operating characteristic curve in the training and validation datasets were 0.720 (95% confidence interval [CI], 0.649-0.791) and 0.704 (95% CI, 0.622-0.786), respectively. An ultrasound-based nomogram was successfully established, of which the predictive model shows excellent predictive performance and can be used to evaluate the status of CLNM in PTMC. Thus, patients with high nomogram scores should be considered for prophylactic central neck dissection.