Application value of superior mesenteric artery-oriented complete mesocolic excision in the treatment of right colon cancer

Objective To investigate the application value of superior mesenteric artery (SMA)-oriented complete mesocolic excision (CME) in the treatment of right colon cancer. Methods The retrospective cohort study was conducted. The clinicopathological data of 955 patients with right colon cancer who were admitted to the First Affiliated Hospital of Nanjing Medical University from January 2013 to June 2018 were collected. There were 514 males and 441 females, aged from 18 to 96 years, with a median age of 65 years. Of the 955 patients, 377 undergoing SMA-oriented CME of right colon with the lymph node dissection along the left boundary of SMA were allocated into SMA-oriented group, and 578 undergoing superior mesenteric vein (SMV)-oriented CME of right colon with the lymph node dissection along the left boundary of SMV were allocated into SMV-oriented group. Observation indicators: (1) intraoperative and postoperative conditions; (2) postoperative complications; (3) postoperative pathological examinations; (4) follow-up and survival situations. Follow-up was performed by telephone interview and outpatient examination once every 3-6 months within 2 years after surgery and once a year after 2 years up to January 2019, using tumor recurrence and metastasis or death as the end point. Follow-up included physical examination and tumor marker test, including carcino embryonic antigen, CA19-9, chest and abdomen CT examination and enteroscopy. Measurement data with skewed distribution were described as M (P25, P75), and comparison between groups was done using the Mann-Whitney U test. Count data were described as absolute numbers or percentages, and comparison between groups was analyzed using the chi square test. Ordinal data were analyzed using the rank sum test. Kaplan-Meier method was used to calculate survival time and rate, and draw survival curve. Log-rank test was used for survival analysis. Patients with loss to follow-up were involved in survival analysis as censored data. Results (1) Intraoperative and postoperative conditions: the operation time, volume of intraoperative blood loss, duration of postoperative hospital stay were 100 minutes (90 minutes, 110 minutes), 50.0 mL (50.0 mL, 70.0 mL), 8 days (8 days, 10 days) in the SMA-oriented group, and 110 minutes (90 minutes, 135 minutes), 50.0 mL (50.0 mL, 122.5 mL), 10 days (8 days, 12 days) in the SMV-oriented group, showing significant differences between the two groups (Z=-5.400, -5.799, -7.461, P 0.05). (2) Postoperative complications: cases with postoperative complications, cases with incisional liquefaction or infection, cases with anastomostic leakage, cases with delayed gastric emptying, cases with intra-abdominal bleeding, cases with complete or incomplete ileus, cases with anastomostic bleeding, cases with intra-abdominal infection, cases with disruption of wound, the number of death were 55, 10, 3, 3, 2, 2, 1, 1, 1, 1 in the SMA-oriented group, which showed no significant difference from 83, 30, 13, 4, 3, 8, 3, 6, 2, 3 in the SMV-oriented group, respectively (χ2=0.045, 3.662, 2.926, 0.034, 0.001, 1.604, 0.352, 1.873, 0.048, 0.352, P>0.05). There were 32 of 377 patients in the SMA-oriented group and 14 of 578 in the SMV-oriented group with chylous leakage, showing a significant difference between the two groups (χ2=18.312, P 0.05). The number of harvested lymph nodes was 22.0 (17.0, 27.0) and 18.0 (15.0, 22.0) in the SMA-oriented group and SMV-oriented group, respectively, with a significant difference between the two groups (Z=-7.800, P 0.05). Conclusion Compared with SMV-oriented CME of right colon, SMA-oriented CME of right colon is safe and feasible, with larger number of harvested lymph nodes, which can achieve complete lymph node dissection. Key words: Colonic neoplasms; Right colon cancer; Complete mesocolic excision; Superior mesenteric artery; Orientation; Chylous leakage; Clinical efficacy