Number of examined lymph nodes and overall survival in intrahepatic cholangiocarcinoma: a population-based study suggesting a staging benefit.

Background: The prognostic role of lymph node yield (LNY) in intrahepatic cholangiocarcinoma (ICC) remains debated. We aimed to clarify the role of LNY by examining its association with nodal detection and overall survival (OS). Methods: We identified patients with surgically resected ICC (2004-2022) from the SEER database. Multivariable Cox models and inverse probability of treatment weighting (IPTW) stratified by nodal status were used to evaluate the association between LNY (≥6 vs <6) and OS. Logistic regression examined predictors of nodal metastasis. Results: LNY ≥6 was not independently associated with OS (HR 0.88, 95% CI 0.71-1.08; P = 0.209). Nodal metastasis (HR 2.29), advanced T category, larger tumor size, poor differentiation, male sex, and lack of chemotherapy were independently associated with worse OS. Notably, multiple tumors were associated with better OS than single tumors (HR 0.79), likely reflecting selection bias. After IPTW, LNY remained non-significant in both the N0 (HR 0.81, 95% CI 0.59-1.11) and N1 (HR 0.95, 95% CI 0.70-1.29) subgroups. Higher LNY was strongly associated with detecting nodal metastasis (OR 4.06, 95% CI 2.99-5.52; P < 0.001). Conclusions: These findings suggest that nodal evaluation in resected ICC primarily improves staging accuracy, and are compatible with-though not directly confirmatory of-the stage-migration hypothesis. Adequate nodal assessment remains important for accurate prognostication, although a modest therapeutic effect of lymphadenectomy cannot be entirely excluded.