Preoperative carbon nanoparticle injection improves inferior mesenteric artery lymph node retrieval in patients with rectal cancer

Inferior mesenteric artery lymph node (station 253 node) metastasis occurs in approximately 0.3% to 13.9% of rectal cancer patients. This study examined whether carbon nanoparticles could aid in harvesting more station 253 nodes and evaluated the relationship between the number of station 253 nodes retrieved and station 253 node metastasis.A total of 480 consecutive rectal cancer patients were enrolled in this prospective cohort study between August 2014 and October 2018. Ninety-one patients (18.96%) received a preoperative submucosal injection of carbon nanoparticles (CN+ group), and 389 patients did not receive an injection (CN- group). The number of lymph node retrievals was analyzed, and the relevant risk factors for station 253 node metastasis were identified using univariate and multivariate analyses.The mean number of station 251, 252, and 253 lymph nodes and total lymph nodes retrieved in the CN+ group were higher than that retrieved in the CN- group. The percentage of patients with ≥4 station 253 nodes retrieved (54.0% vs 28.3%, P = .004) were higher in the CN+ group than in the CN- group. Retrieval of ≥4 station 253 nodes was an independent risk factor for station 253 node metastasis (OR: 2.40, 95% CI: 1.22-4.74, P = .012).The preoperative submucosal injection of carbon nanoparticles was helpful for increasing the number of station 253 nodes harvested, and a minimum of 4 examined station 253 nodes was necessary for standard D3 lymph node dissection in rectal cancer.