Abstract Background This study aimed to compare clinicopathological features and recurrence risk in clinically node-negative (cN0) solitary isthmic papillary thyroid microcarcinoma (PTMC) ≤ 5 mm and > 5 mm in diameter treated with isthmusectomy, and to identify predictors of recurrence. Methods A retrospective review was performed of 201 cN0 patients with solitary isthmic PTMC who underwent isthmusectomy between 2018 and 2024. Patients with preoperative high-risk features were excluded. Subgroup analysis compared clinicopathological characteristics between the ≤ 5 mm ( n = 107) and > 5 mm ( n = 94) groups. Univariate and multivariate Cox models were used to identify factors associated with recurrence-free survival (RFS). Results Significant differences were observed between the two groups in tumor size ( p 5 mm ( p = 0.028), CLNM ( p = 0.002), and a higher number of metastatic central lymph node (CLN) ( p 3 as the optimal cut-off for predicting recurrence. Kaplan–Meier analysis demonstrated worse RFS in patients with tumors > 5 mm ( p = 0.031). Multivariate analysis confirmed metastatic CLNs > 3 as an independent predictor of recurrence (HR 5.298, 95% CI 1.473–19.060, p 5 mm were associated with a higher risk of recurrence. In addition, CLNM, especially a metastatic CLNs > 3, may have prognostic significance and should be considered in surgical decision-making for isthmic PTMC.
Zhu et al. (2026) studied this question.