Effects and risk factors of low ligation of the inferior mesenteric artery on the third station lymph node dissection and metastasis in laparoscopic radical resection of rectal cancer / 中华消化外科杂志

ABSTRACT

Objective To explore the effects of low ligation of the inferior mesenteric artery (IMA) on the third station lymph node dissection in laparoscopic radical resection of rectal cancer (RC),and analyze the risk factors affecting the third station lymph node metastasis.Methods The retrospective cohort study was conducted.The clinical data of 380 RC patients who were admitted to Renji Hospital of Shanghai Jiaotong University School of Medicine from June 2014 to June 2016 were collected.Of 380 patients,177 with preservation of left colic artery (LCA) and 203 without preservation of LCA were respectively allocated into the low ligation group and high ligation group.All the patients received laparoscopic radical resection of RC based on the principle of total mesorectal excision (TME).Observation indicators(1) intra-and post-operative recovery situations;(2) results of postoperative pathological examination;(3) follow-up and survival;(4) risk factors analysis affecting the third station lymph node metastasis.Follow-up using outpatient examination and telephone interview was performed to detect postoperative disease-free survival and tumor recurrence or metastasis up to May 31,2017.Measurement data with normal distribution were represented as x ± s,and comparisons between groups were evaluated with the t test.Comparisons of count data and ordinal data were respectively analyzed using the chisquare test and U test.The survival curve and survival rate were respectively drawn and analyzed using the KaplanMeier method,and the survival analysis was done by the Log-rank test.Results (1) Intra-and post-operative recovery situationsall the patients underwent successful surgery.The operation time,time to initial exsufflation and cases with anastomotic leakage were respectively (147.2±3.0) minutes,(72.8± 1.4)hours,20 in the low ligation group and (137.2±2.8) minutes,(76.6± 1.1) hours,38 in the high ligation group,with statistically significant differences between groups (t =2.463,2.073,x2 =4.025,P＜0.05).Volume of intraoperative blood loss,cases with temporary stoma,vascular injury (injury of inferior mesenteric vessels and presacral vein injury),urinary retention and duration of postoperative hospital stay were respectively (119±6)mL,25,29,24,(10.7± 0.5)days in the low ligation group and (108±5)mL,32,27,30,(9.6±0.4)days in the high ligation group,with no statistically significant difference between groups (t=1.524,x2 =0.235,0.716,1.115,t=1.780,P＞ 0.05).Of 58 patients with anastomotic leakage,31 received previously terminal loop ileostomy,13 received conservative treatment and 14 received postoperatively terminal loop ileostomy.Fifty-four patients with urinary retention received urethral catheterization.All the patients with complications were improved by treatment and then were discharged.(2) Results of postoperative pathological examinationnumber of lymph node dissected in the low ligation group and high ligation group was respectively 12.8±0.4 and 12.0±0.3;cases with depths of tumor invading to intestinal wall in stage pT1-T2 and pT3-T4,with tubular adenocarcinoma and non-tubular adenocarcinoma,with high-differentiated,moderate-differentiated and low-differentiated tumors,with lymph node metastasis in stage N0,N 1 and N2,with and without the third station lymph node metastasis,with TNM staging in stage Ⅰ,Ⅱ,Ⅲ,and Ⅳ were respectively 53,124,150,27,81,63,33,73,66,38,16,161,17,54,93,13 in the low ligation group and 59,144,176,27,99,59,45,79,78,46,24,179,32,47,105,19 in the high ligation group,with no statistically significant difference in above indicators between groups (t =1.556,x2 =0.035,0.296,U=2.002,0.220,x2 =0.778,U=5.557,P＞0.05).(3) Follow-up and survival338 of 380 patients were followed up for 6-36 months,with an average time of 28 months,including 164 in the low ligation group and 174 in the high ligation group.The 1-and 3-year disease-free survival rates and cases with postoperative tumor recurrence or metastasis were respectively 93.9％,76.4％,39 in the low ligation group and 94.8％,79.3％,36 in the high ligation group,with no statistically significant difference between groups (x2=0.861,P＞0.05).(4) Risk factors analysis affecting the third station lymph node metastasisresults of univariate analysis showed that tumor location and diameter,depth of tumor invading to intestinal wall and tumor histopathological type were related factors affecting the third station lymph node metastasis of RC patients (x2 =9.957,9.921,6.196,6.576,P＜0.05).Results of multivariate analysis showed that tumor diameter ＞ 5 cm and non-tubular adenocarcinoma were independent risk factors affecting the third station lymph node metastasis of RC patients (Odds ratio=2.561,2.296,95％ confidence interval1.280-5.123,1.037-5.083,P＜0.05).Conclusions The low ligation of the IMA is safe and feasible in laparoscopic radical resection of RC,meanwhile,it has the same radical effect in lymph node dissection and doesn't affect the third station lymph node metastasis and shortterm disease-free survival compared with high ligation of the IMA.Tumor diameter ＞ 5 cm and non-tubular adenocarcinoma are independent risk factors affecting the third station lymph node metastasis of RC.