A Nomogram for Lateral Lymph Nodes that have Metastatic Cn0 Unifocal Papillary Thyroid Microcarcinoma

Author(s): Hassan A. Saad, Mohamed I Farid, Mohamed E Eraky, Ahmed K. El-Taher,Khaled Sharaf, Azza Baz, Mohamed Riad

Background: The need for lateral neck dissection (LND) for papillary thyroid microcarcinoma (PTMC) can be better understood by identifying risk variables for occult lateral lymph node metastasis (LLNM). This study aimed to create a nomogram to predict the likelihood of LLNM in individuals with cN0 unifocal PTMC.

Methods: A total of 9744 patients with cN0 unifocal PTMC who were treated at our facility between February 2013 and April 2020 were included in our retrospective analysis. Risk variables for LLNM were identified using logistic regression analysis, and a nomogram was created based on these risk factors.

Results: In the study population, 3.2% had LLNM. Compared to tumors in the lower or middle lobe with a size less than or equal to 7 mm, tumors 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 tumors 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 compared to those who did not (OR = 2.91, 95% CI 1.93-4.42; p 0.001). The receiver operating characteristic (ROC) curve of a nomogram considering these risk factors 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 tumors >7 mm in size were independent risk factors for LLNM in patients with cN0 unifocal PTMC. Based on these variables, the nomogram showed a good predictive value and consistency.