Therapeutic Index Associated with Lymphadenectomy Among Patients with Intrahepatic Cholangiocarcinoma: Which Patients Benefit the Most from Nodal Evaluation?

Background Although lymph node metastasis (LNM) is an important prognostic indicator for patients with intrahepatic cholangiocarcinoma (ICC), the benefit and indication for lymphadenectomy remain unclear. Methods Patients diagnosed with ICC between 1990 and 2016 were identified in the international multi-institutional dataset. To determine the survival benefit from lymphadenectomy, the therapeutic index was calculated by multiplying the frequency of LNM in a particular group of patients by the 3-year cancer-specific survival (CSS) rate of patients with LNM in that subgroup. Results Among 471 patients who met the inclusion criteria, approximately half had LNM (n = 205, 43.5%). The median number of resected and metastatic LNs were 4 [interquartile range (IQR) 2-8] and 0 (IQR 0-1), respectively. Three-year CSS in the entire cohort was 29.9%, reflecting a therapeutic index value of 13.0. The therapeutic index was lower among patients with major vascular invasion (5.4), preoperative carcinoembryonic antigen (CEA) > 5.0 (8.2), and LNM in areas other than the hepatoduodenal ligament (5.2). Of note, a therapeutic index difference of more than 10 points was noted only when examining the number of LNs harvested [1-2 (4.1) vs. 3-6 (16.1) vs. >= 7 (17.8)]. Conclusion The survival benefit derived from lymphadenectomy was poor among patients with major vascular invasion, CEA > 5.0, and LNM in areas other than the hepatoduodenal ligament. Resection of three or more LNs was associated with the highest therapeutic value among patients with LNM.