Factors Associated with Level II and V Involvement in Lateral Neck Dissection for pN1b Papillary Thyroid Carcinoma

Background: Lateral neck dissection is the standard surgical treatment for patients with papillary thyroid carcinoma (PTC) and lateral cervical lymph node metastases (pN1b). However, the optimal extent of dissection remains debated, particularly for levels II and V. We examined patterns of nodal involvement and factors associated with metastases at these levels. Methods: This single-center retrospective study included 70 patients with pN1b PTC who underwent lateral neck dissection between 2019 and 2025. Demographic, clinical, surgical, and pathological variables were analyzed. The lymph node ratio (LNR), defined as metastatic nodes divided by harvested nodes, was dichotomized at the cohort median. Bivariate associations were assessed using Pearson’s χ2 test, Fisher’s exact test, or the Fisher–Freeman–Halton exact test, as appropriate; p < 0.05 indicated statistical significance. Results: Median age was 46 years and 60% were female. Involvement was highest at levels III (82.9%) and IV (65.7%), followed by II (55.7%) and V (23.9%). Median LNR was 0.25. Level II involvement was more frequent in male patients (71.4% vs. 45.2%; p = 0.031) and patients with high versus low LNR (76.5% vs. 36.1%; p = 0.001). Histological subtype was associated with level V involvement (p = 0.027), predominantly in classic PTC. Conclusions: Male sex and higher LNR were associated with level II involvement in bivariate analyses; an exploratory association was also observed between histological subtype and level V involvement. These findings do not establish independent predictors or justify altering the extent of neck dissection. Larger cohorts and multivariable analyses should validate these findings.