Indocanine Green as Tracer for Lymph Nodes Dissection in Station 253 of Rectal and Sigmoid Colon Carcinoma

ICG is a registered and FDA-approved non-specific fluorescent probe for optical imaging in clinical settings. The properties of ICG ,which is a water-soluble amphiphilic molecule with a molecular weight of 775 Dalton and a hydrodynamic diameter of 1.2nm ,render it an excellent lymphatic contrast agents if injected into the lymphatic system. ICG near-infrared(NIR) fluorescent imaging has achieved satisfactory results in the localization of sentinel lymph nodes in patients with breast cancer,non-small cell lung cancer,and gastric cancer. Liang et al have suggested that 253 lymph nodes dissection in rectal cancer is technically demanding ,and that learning curve for laparoscopic 253 lymph nodes dissection requires minimally 20 procedures. Currently,it was still controversial about 253 lymph nodes dissection in rectal cancer surgery. However, lymph node involvement is a major prognostic factor for survival after rectal cancer surgery. Therefore, it is necessary to harvest more station 253 nodes for the better long-term survival and the more precise staging.

In this study, investigators will randomly assign patients to the indocanine green (ICG) group and control (CL)group. Number of harvested station 253 lymph nodes, number of positive station 253 lymph nodes, will be evaluated and compared. Investigators will also evaluate patients, operative time, blood loss, post-operative hospital stay and complications.