A nomogram for lateral lymph nodes that have metastatic cN0 unifocal papillary thyroid microcarcinoma

Abstract Background The need for lateral neck dissection (LND) in papillary thyroid microcarcinoma (PTMC) might be better understood by identifying risk variables for occult lateral lymph node metastasis (LLNM). This study's goal was to create a nomogram for predicting the likelihood of LLNM in individuals with cN0 unifocal PTMC. Methods A total of 9744 patients with cN0 unifocal PTMC who had treatment at our facility between February 2013 and April 2020 were the subject of our retrospective analysis. The risk variables for LLNM were identified using logistic regression analysis, and a nomogram was created based on these risk factors. Results 3.2% of the population had LLNM. Compared to tumours in the lower or middle lobe with a size less than or equal to 7 mm, tumours in the upper lobe had a substantially increased risk of LLNM (odds ratio [OR] = 2.56, 95% confidence interval [CI] 1.80–3.62; p 0.001) and OR = 2.59, 95% CI 1.85–3.62. ETE tumours had a significantly increased probability of developing LLNM (OR = 1.41, 95% CI 1.01–1.99; p = 0.044). One or two central lymph node metastases (CLNMs) or three or more of them (OR = 5.84, 95% CI 3.83-8.93; p 0.001) increased the probability of LLNM in comparison to having none (OR = 2.91, 95% CI 1.93-4.42; p 0.001). The receiver operating characteristic (ROC) curve of a nomogram that took these risk factors into account showed an area under the curve (AUC) of 0.777, indicating a good level of predictive accuracy. Conclusion Three or more CLNMs, especially three or more, and upper lobe tumours larger than 7 mm in size were independent risk factors for LLNM in cN0 unifocal PTMC. Based on these variables, the nomogram showed good predictive value and consistency.