Predictive nomogram for occult metastasis in central lymph nodes of papillary thyroid microcarcinoma based on clinical and ultrasound features.

Background: Papillary thyroid microcarcinoma (PTMC) is prone to central lymph node metastasis (CLNM), and precise preoperative identification is crucial for the establishment of surgical protocol. We aimed to develop a nomogram based on clinical and ultrasound features to predict the presence of occult CLNM in clinically lymph node-negative (cN0) PTMC patients.

Methods: We included 844 patients with cN0 PTMC admitted to The First Affiliated Hospital of Nanchang University between January 2022 and December 2023 who underwent thyroidectomy. Clinical and ultrasound characteristics were collected for univariate and multivariate analyses to determine the risk factors for CLNM metastasis, with consequent establishment of nomograms and internal validation.

Results: A total of 303 patients with cN0 PTMC had CLNM (35.9%), and multifactorial analysis showed that male [odds ratio (OR) =2.96, 95% confidence interval (CI): 1.90-4.61, Ρ<0.001], age <55 years (OR =1.91, 95% CI: 1.20-3.04, Ρ=0.006), multifocal (OR =2.10, 95% CI: 1.43-3.09, Ρ<0.001), isthmus (OR =3.37, 95% CI: 1.42-8.03, Ρ=0.006), microcalcification (OR =2.02, 95% CI: 1.38-2.96, Ρ<0.001), and tumor size (OR =2.27, 95% CI: 1.47-3.49, Ρ<0.001) were independent risk predictors. The nomogram had good predictive ability. The area under the curve (AUC) of receiver operating characteristic (ROC) was 0.746 (95% CI: 0.704-0.789) in the training set and 0.726 (95% CI: 0.663-0.790) in the validation set. In addition, calibration curves were well fitted and decision curve analysis (DCA) indicated that patients could benefit clinically.

Conclusions: The nomogram established in our study has a certain predictive ability for CLNM, which can be applied to the clinical management of cN0 PTMC patients, so as to provide more accurate preoperative evaluation and develop better treatment strategies.