Lymph node yield ≥4 is associated with improved overall and cancer-specific survival after resection of cholangiocarcinoma: a population-based SEER analysis, 2004-2015.

INTRODUCTION: Regional lymphadenectomy is standard in curative-intent resection of cholangiocarcinoma (CCA), but the optimal lymph node yield remains uncertain. We assessed the association between lymph node yield and overall (OS) and cancer-specific (CSS) survival. MATERIALS AND METHODS: Patients with histologically confirmed CCA (C22.1/C24.0; ICD-O-3 8160/8162/8140) who underwent cancer-directed surgery between 2004 and 2015 were identified from the SEER 17-registry database. Lymph node yield was categorized as ≥4 nodes, 1-3 nodes, or none. Multivariable Cox models were adjusted for age, sex, site, year, grade, AJCC stage, chemotherapy and radiotherapy. RESULTS: Among 1952 surgical patients, 1261 (64.6%) had ≥4 nodes and 674 (34.5%) had 1-3 nodes. Lymph node yield ≥4 was independently associated with improved OS (HR 0.84, 95% CI 0.75-0.94, p = 0.002) and CSS (HR 0.81, 95% CI 0.72-0.92, p = 0.001). The benefit was significant in extrahepatic/hilar CCA (HR 0.75, 95% CI 0.66-0.86, p < 0.001) and stage I-II disease (HR 0.84, 95% CI 0.74-0.97, p = 0.013), but not in intrahepatic CCA (HR 1.04, 95% CI 0.86-1.26, p = 0.70). CONCLUSION: A lymph node yield of ≥4 was independently associated with improved OS and CSS after resection of CCA, with the benefit most pronounced in extrahepatic/hilar tumors, supporting adequate regional lymphadenectomy.