Research On The Application Of Laparoscopic Selective Lateral Lymph Node Dissection For Low Rectal Cancer

Objective:To analyze the safety and feasibility of laparoscopic selective lateral lymph node dissection(LLND)for low rectal cancer and the risk factors of lateral lymph node metastasis(LLNM)in low stageⅡ～Ⅲrectal cancer.Methods:Collecting the data of patients with rectal cancer treated by laparoscopic radical resection in the Northern Jiangsu People’s Hospital from August 2019 to November2020.The paper included 62 cases following the inclusion and exclusion criteria.Among them,32 cases underwent laparoscopic radical resection of rectal cancer(the TME group),30 cases underwent laparoscopic radical resection combined with selective lateral lymph node dissection(the selective LLND group).The software SPSS 26.0 was used for statistical analysis,analyzing the basic data,intraoperative condition,and postoperative recovery,to evaluate the safety and feasibility of the surgery.According to whether the lateral lymph node(LLN)dissected is positive,the patients were divided into LLN-negative and LLN-positive two groups.Based on selective LLND,we analyzed the clinical and pathological features.The univariate analysis screened out the significant risk factors,and the independent risk factors of LLNM for stageⅡ～Ⅲlow rectal cancer were screened out by logistic regression analysis.Results:62 patients in total,among them,32 cases underwent laparoscopic TME,30cases underwent laparoscopic selective LLND.The clinical baseline data of the two groups:gender,age,ASA grade,BMI,preoperative chemoradiotherapy,preoperative CEA,abdominal operation history,tumor long diameter,distance from inferior margin to anus,and TNM stage had no significant difference.Operation time was significantly shorter[145.5(118-258)min and 246.5(179-405)min,Z=-5.169,P<0.001]in the TME group.In the TME and selective LLND groups,the intraoperative blood loss was 56(25～500)ml and 68(45～500)ml,the postoperative ventilation time was 3(1～6)d and 2.5(1～6)d,the postoperative hospital stay was 10(6～24)d and 9(7～23)d,and the hospitalization cost was 4.8(4.3～6.7)and 4.8(4.4～6.8)million yuan,and without statistical difference.Lymph node dissection in the selective LLND group is more thorough[27.5(17～38)vs19.0(9～35),P=0.001],and the remaining pathological indicators,such as T stage and N stage had no significant difference.8(6～16)was the number of LLND,and 7 of 30 patients had lateral lymph node metastasis,including 14 regions,including internal iliac region(n=6),obturator area(n=7),and external common iliac region(n=1),with a metastasis rate of23.3%.The incidence of perioperative complications in the TME group and the selective LLND group was 18.8%and 23.3%,respectively,and without significant difference.There was 1 case of anastomotic leakage(grade III to IV complications)in both groups,5 cases of grade I to II complications in the TME group,and 6 cases of grade I to II complications in the selective LLND group,which was not statistically significant(P=1.000,based on Clavien-Dindo classification).The overall survival rates in the follow-up period of 2 to 18months were similar(90.6%vs 90.0%)between the two groups,with no statistical significance(X~2=0.701,P=0.402).While the total local recurrence rate of patients in the selective LLND group(6.3%vs 0%)was lower.But it was not statistically significant due to the short and inconsistent follow-up time.Univariate analysis of LLNM in low stageⅡ～Ⅲrectal cancer showed that there was a significant difference between lateral lymph node negative group and positive group in tumor differentiation(P=0.007)and upper lymph node metastasis(P=0.031).There was no significant difference in gender,age,family history,tumor long diameter,gross type,circumference of tumor invasion,location of tumor in the intestine,preoperative CEA,and depth of tumor invasion.According to the regression analysis,the risk of LLNM in poorly differentiated patients is 11.809 times higher than that in patients with well-differentiated adenocarcinoma.And the independent risk factor of LLNM was the degree of tumor differentiation(OR=11.809,95%CI=1.335～104.493,P=0.026).Conclusion:First of all,selective laparoscopic LLND for rectal cancer will not increase the amount of intraoperative blood loss,affect postoperative recovery and increase the incidence of postoperative complications;secondly,compared with prophylactic LLND,selective LLND can obtain a higher rate of lateral lymph node metastasis and avoid unnecessary dissection.Therefore,laparoscopic selective LLND is safe,feasible and meaningful.At the same time,the risk of LLNM in middle and low stageⅡ～Ⅲstage poorly differentiated rectal adenocarcinoma is high,which can be evaluated by pelvic MRI.If there is suspected LLNM,and there is no serious underlying disease in anesthesia evaluation,LLND can be selectively considered.