[Application of carbon nanoparticles mapping lymph nodes in curative resection for colorectal carcinoma]

Objective: To investigate the clinical application of carbon nanoparticles mapping lymph nodes in curative resection for colorectal carcinoma. Methods: Patients diagnosed with colorectal cancer before operation and undergoing radical surgery with intact postoperative pathological data in the Sixth Affiliated Hospital, Sun Yat-sen University from March 2016 to March 2018 were included in this retrospective case-control study. Those who were diagnosed with ileus, recurrent carcinoma or underwent emergency operation were excluded. A total of 1421 cases were included, with 156 cases in the carbon nanoparticles mapping group and 1265 cases in the control group. Using 1∶3 case control matching based on gender, weight, TNM staging and neoadjuvant chemotherapy, 145 and 435 cases were finally recruited in the carbon nanoparticles mapping group and control group, respectively. Patients in the carbon nanoparticles mapping group underwent preoperative colonoscopy with carbon nanoparticles submucosal injection 2.4 (1.0 - 14.0) days before operation. Carbon nanoparticles of 0.25 ml was injected at 4 points (3, 6, 9 and 12 o'clock each) 0.5-1.0 cm around the tumor. The number of eliminated lymph node, number of positive lymph node and positive rate between the two groups were compared, and the number of eliminated lymph node in different subgroups of T stage, N stage, TNM stage and neoadjuvant chemotherapy was analyzed and compared. Results: After case control matching, total number of eliminated lymph nodes in the carbon nanoparticles mapping group was significantly higher than that in the control group (22.2±11.2 vs. 19.0±9.5, t=3.025, P=0.003). However, no statistically significant differences were found in the number of positive lymph node and lymph node positive rate between two groups (all P>0.05). Subgroup analysis showed that as compared to the control group, total number of eliminated lymph nodes in the carbon nanoparticles mapping group was significantly higher in T3 stage subgroup (median: 22 vs. 18, Z=2.435, P=0.015), N0 stage subgroup (median: 20.5 vs. 17.5, Z=2.772, P=0.006), TNM II stage subgroup (median: 23.5 vs. 19.0, Z=2.654, P=0.008) and neoadjuvant chemotherapy (median: 22.5 vs. 13.0, Z=3.287, P=0.001), while compared to the control group, the number of positive lymph node (median: 4.0 vs. 6.5, Z=-2.530, P=0.011) and the lymph node metastasis degree (median: 16% vs. 31%, Z=-2.862, P=0.004) were lower in the carbon nanoparticles mapping group in N2 subgroup. Conclusion: Carbon nanoparticles mapping lymph nodes can effectively enhance the number of eliminated lymph nodes in curative resection for colorectal cancer.