Laparoscopic D2 lymph node dissection (LND) for gastric cancer has a wide range of operations and a high degree of difficulty.The purpose of this study was to evaluate the relationship between clinicopathological factors and the difficulty of laparoscopic D2 LND.

Inclusion Criteria:

1. all patients undergoing laparoscopic surgery
2. Laparoscopic system is 2D and has complete D2 lymph node dissection.

Exclusion Criteria:

1. patients undergoing laparotomy
2. incomplete video or clinicopathological information

The CLASS-01 trial is a prospective multicenter randomized controlled study (ClinicalTrials.gov.number:NCT01609309) to compare the oncological efficacy of laparoscopy and laparotomy in the treatment of locally advanced distal gastric cancer. In this study, 119 patients who underwent laparoscopic surgery at our center who participated in CLASS-01 were selected. All the patients were operated with 2D laparoscopic system.The 2D/3D trial is a prospective clinical trial (ClinicalTrials.gov.number:NCT02327481) that compares the curative effect of 2D and 3D laparoscopic radical gastrectomy in our center. Seventy cases of 2D laparoscopic distal gastrectomy (LDG) were selected