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[Clinical value of carbon nanoparticles tracer in gastric cancer surgery to increase the number of lymph nodes retrieval].

Objective: To investigate the clinical value of carbon nanoparticles zonal tracer technique in lymph node retrieval of gastric cancer (GC). Methods: A retrospective cohort study was carried out. Clinicopathological data of GC patients who underwent radical D2 resection with carbon nanoparticles tracer in The First Affiliated Hospital of Hainan Medical University and Hainan Cancer Hospital from December 2015 and February 2019 were collected. Those with postoperative pathology of T1-2, Borrmann IV type GC, distant metastasis, preoperative neoadjuvant chemotherapy and incomplete data were excluded. A total of 181 patients were enrolled in this study, including 113 cases from the First Affiliated Hospital of Hainan Medical University and 68 cases from Hainan Cancer Hospital. Patients were categorized into two groups based on the methods of carbon nanoparticles tracer: zonal tracer group and traditional tracer group. In the traditional tracer group, 0.1-0.3 ml of carbon nanoparticle was injected subserously at the upper, lower, left and right 4 injection points 0.5 cm away from the edge of the tumor in the normal serous membrane. In the zonal tracer group, on the basis of the traditional tracer group, 0.1-0.3 ml of carbon nanoparticle was injected subserously at the first branch of the suprapyloric right gastric artery into the stomach, the first branch of the subpyloric right gastroepiploic artery into the stomach, the first branch of the minor curvature left gastric artery into the stomach and the first branch of the greater curvature left gastroepiploic artery into the stomach, respectively. The display of lymphatic vessels in each location and lymph nodes in each group by the tracing method was observed. The number of black-stained lymph nodes, the black staining rate of lymph nodes, the total number of detected lymph nodes, the total number of positive lymph nodes, and the metastatic rate of lymph node were compared between the two groups. Results: Eighty-nine patients were assigned to zonal tracer group, and 92 patients to traditional tracer group. There were no significant differences in baseline information between the two groups (all P>0.05). The median number of black-stained lymph nodes (median: 25.0 vs. 13.5, Z=-7.158, P<0.001) and the black staining rate of lymph nodes [(70.8±12.0)% vs. (47.1±15.7)%, t=11.399, P<0.001) in the zonal tracer group were significantly higher than those in the traditional tracer group. The total detected number of lymph nodes (37.5±11.5 vs. 29.6±11.8, t=4.581, P<0.001) and the total number of negative lymph nodes (31.3±12.5 vs. 24.9±11.1, t=3.621, P<0.001) were significantly higher in the zonal tracer group than those in the traditional tracer group. There were no significant differences in the total number of positive lymph nodes (median: 4.0 vs. 3.0, Z=-1.485, P=0.137), lymph node metastatic rate [78.7% (70/89) vs. 72.8% (67/92), χ(2)=0.834, P=0.361] and metastatic degree [median: 11% vs. 10%, Z=-0.483, P=0.629] between the two groups. Conclusion: The carbon nanoparticles zonal tracer method can increase the black-staining rate of lymph nodes and the detected number of lymph nodes, thus improving the accuracy of gastric cancer staging.