The role of lymph node dissection and a new N-staging system for intrahepatic cholangiocarcinoma: a study from the SEER database

BACKGROUND: Although the National Comprehensive Cancer Network guidelines recommend routine lymph node dissection (LND) in intrahepatic cholangiocarcinoma (ICC), the role of LND remains controversial, and the node (N) stage is oversimplified. METHODS: Patients were identified from the Surveillance, Epidemiology, and End Results research data 18 (SEER 18). Propensity score matching (PSM) was used to reduce bias, and Kaplan–Meier curves and Cox proportional hazards models were used to compare overall survival (OS). The best cutoff values were found using X-tile software. RESULTS: Of 2037 patients included in SEER 18, 1147 underwent LND (56.3%); 389 (34.3%) had pathologically confirmed lymph node metastasis (LNM), and 316 (27.6%) had at least 6 LNDs. The median OS was worse for LND patients (34 months vs. 40 months, respectively), and this result remained after PSM. Male sex, age ≥60 years, tumor size > 5 cm, and LNM were independent prognostic risk factors for ICC. LNM ≥3 was associated with worse OS. CONCLUSIONS: Only a few LNDs met the requirements per the guidelines. LND does not improve OS in ICC, and the best approach to LND and a better N staging method should be explored further.