Patterns and prognostic value of lymph node dissection for resected perihilar cholangiocarcinoma

Background and Aim: Lymph node metastasis is a major prognostic factor for perihilar cholangiocarcinoma (PHC). However, prognostic significance of extent of node dissection, lymph node ratio (LNR), and number and location of positive nodes remain unclear. We aimed to evaluate whether node status, LNR, or number or location of positive nodes are independent factors for staging in PHC and to determine the minimum requirements for node examination. Methods: The Surveillance, Epidemiology, and End Results database was used to identify 1116 resected PHCs from 1998 to 2008. The correlation between nodal status and survival was analyzed retrospectively. Results: Lymph node metastasis occurred in 43.4% patients and was an independent predictor for overall survival and cancer-specific survival. No survival benefit was observed for an increasing number of node retrieval in node-positive patients. However, in node-negative patients, ≥13 node dissection was of more survival benefit than 3≤total lymph node count (TLNC)≤12 and TLNC<3 (5-year overall survival: 52.8% vs 39.7% vs 26.3%, P=0.001; 5-year cancer-specific survival: 60.6% vs 46.3% vs 30.0%, P=0.001). No difference in survival between patients with regional and distant node involvement was found. Survival for patients with greater than three positive nodes was significantly worse than that for those with three or less (relative ratio: 1.466, P=0.001). And patients with LNR>0.27 also had unfavorable prognosis (relative ratio: 1.376, P=0.001). Conclusions: We determined that to adequately assess nodal status of this life-threatening disease, 13 or more nodes retrieval should be considered. Number of positive nodes and LNR rather than location of metastatic nodes may be defined as parameters for staging of PHC.