Background : Several guidelines recommend lymph node dissection (LND) for intrahepatic cholangiocarcinoma (ICC) during the surgery. However, there is no evidence about whether additional LND or not for incidentally known ICC. The study aims to identify the patients who will benefit from LND for incidental ICC.

Methods : From 2000 to 2019, 212 patients who underwent hepatectomy for ICC were enrolled in the study. The enrolled patients were subdivided according to T stage. (T1, T2 and T3+4) Survival outcomes of each subgroup, including disease-free survival (DFS) and overall survival (OS) were analyzed according to nodal status. (Nx vs. N0 vs. N1).

Results : In the DFS analysis, only Nx patients of T1 group showed more favorable survival outcomes than N1 patients of T1 group and Nx patients of T2 and T3+4 group showed similar outcomes to N0 patients of each group. (Nx vs. N1 (months): T1 group, 133.0 [13.5-232.5] vs. 8.0 [0.0-25.6], p=0.004; T2 group, 11.0 [1.0-21.0] vs. 7.0 [1.8-12.2], p=0.073; T3+4 group, 12.0 [4.1-19.9] vs. 5.0 [1.6-8.4], p=0.109) In the OS analysis, similar results were shown. (Nx vs. N1 (months): T1 group, 157.0 [96.0-218.0] vs. 22.0 [0.0-52.3], p<0.001; T2 group, 34.0 [11.9-56.1] vs. 25.0 [15.1-34.9], p=0.079; T3+4 group, 20.0 [0.0-71.9] vs. 15.0 [7.4-22.6], p=0.266)

Conclusions : Incidental ICC without LND above T1 patients are recommended additional LND.