Objective  To evaluate the clinical value of activated carbon nanoparticles for guiding lymphadenectomy in advancing rectal cancer.

  Methods  Eighty rectal cancer patients who underwent laparoscopic curative resection for rectal cancer were divided into two groups: control group (40 cases) and experiment group (40 cases). The experiment group received carbon nanoparticle-labeled lymph nodes in surgery. The number of lymph nodes, lymph nodes ≤5 mm in size, and positive lymph nodes, as well as the side effect of the procedure, were analyzed.

  Results  No complications were observed in the experiment group. The experiment group showed significantly higher values (P<0.05) than the control group for average number of lymph nodes (25.5 ± 8.78 vs. 16.05 ± 4.84), lymph nodes ≤5mm in size (22.6±8.25 vs. 13.65±4.62), and positive lymph nodes (3.13±4.14 vs. 1.35±2.06). During operation, two dyed lymph nodes in two cases were found at the roof of the inferior mesenteric artery and along the side of the internal iliac artery. Dissection was extended for these patients and the dyed lymph nodes were confirmed to be positive.

  Conclusion  Local injection of activated carbon nanoparticles around the tumor during surgical exploration was an effective, secure, and easy approach for guiding lymphadenectomy in rectal cancer patients.