Impact of lymph node dissection on clinical outcomes of intrahepatic cholangiocarcinoma: Inverse probability of treatment weighting with survival analysis

BACKGROUND: Lymph node metastasis (LNM) has been established as a critical risk factor for prognosis in intrahepatic cholangiocarcinoma (ICC). The clinical implications of lymph node dissection (LND) have been debated. This study aimed to clarify the prognostic impact of LND by multicenter retrospective analysis. METHODS: A total of 310 ICC patients who had undergone curative resection between 2000 and 2016 were retrospectively analyzed. The prognostic impact of LND was estimated under an inverse probability of treatment weighting (IPTW) approach using propensity scores. RESULTS: LND was performed for 224 patients (72%), with LNM pathologically confirmed in 90 patients (40%). Prognosis was poorer for patients with LNM (median survival, 16.9 months) than for those without (57.2 months; P < .0001). One‐, 3‐, and 5‐year overall survival rates (OS) were comparable among LND+ (81.6%, 48.0%, and 37.5%, respectively) and LND– groups (81.6%, 55.4%, and 44.6%, respectively). However, advanced tumor, as characterized by larger tumor, multinodular lesions, and serosal invasion, was significantly more frequent in the LND+ group than in the LND– group. After IPTW adjusting for imbalances, 1‐, 3‐, and 5‐year OS were better in the LND+ group (83.5%, 52.2%, and 42.8%, respectively) than in the LND– group (71.9%, 32.4%, and 23.4%, respectively; P = .046). LND thus showed significant prognostic impact (hazard ratio = 0.58, 95%CI = |0.39|–|0.84|, P = .005), especially in hilar ICC. However, peripheral ICC displayed no therapeutic benefit from LND. CONCLUSIONS: LND could have a significant role to play in improving oncologic outcomes. Therapeutic LND should be implemented on the basis of tumor location and tumor advancement.