Figure 1. Schematic of process for enrolling patients.

A total of 733 patients were diagnosed with ICC and confirmed pathologically from January 2009 to December 2014. We excluded 54 patients with preoperative treatment; 15 patients were excluded for other accompanying malignancies; 28 patients were excluded because they only received a laparotomy and biopsy. Evidence of LNM, either by intraoperative palpation or by positive imaging examination before operation, was defined as clinical Lymph Node Metastasis (cLNM). After evaluation, 422 patients were finally enrolled in the study.