The Study On Minimally Invasive Surgical Treatment Of Right-sided Colon Cancer

Background:Colorectal cancer(CRC)is the most common malignancy of the gastrointestinal system and the surgery is the main treatment for non-metastatic colorectal cancer.The principle of surgical treatment of colon cancer was relatively stable until the D3 radical surgery and Complete Mesocolon Excision(CME)was proposed by Japanese and European surgeons.This CME concept has shed light upon surgical treatment of right-sided colon cancer.Meanwhile,researchers have realized that the lymph node metastatic routes of right-sided colon cancer may be varied according to different tumor location,which makes the choice of surgical approaches for specific right-sided colon cancer debatable.With the development of minimally invasive techniques,surgeons are pursuing pure laparoscopic surgery.The safety and efficacy of intracorporeal anastomosis gradually poses a concern for specialists.The evaluation and validation of new surgical technologies and concepts depends on rigorous clinical researches.Our study was intended to conduct comparative effectiveness researches from the following three aspects to analyze the problems mentioned above based on the single-center or multi-center prospective database,namely the extension of lymphadenectomy for laparoscopic right hemicolectomy,the different surgical approaches for mid-transverse colon cancer and the intracorporeal or extracorporeal anastomosis in laparoscopic right hemicolectomy.Methods:The prospective CRC database of our single institution was established to collect baseline characteristics,surgical,postoperative and long-term outcomes of CRC patients undergoing surgical treatment.Additionally,our insititution also conducted and participated in a national multi-center randomized controlled trial(RCT)--RELARC trial,which was aimed to compare the short-term and long-term outcomes of laparoscopic right hemicolectomy CME surgery with D2 surgery.The clinical data was collected meticulously and stored independently in a specialized data management system.The primary outcome of RELARC trial are still under follow-up.This study was intended to retrospectively analyze the data from the database mentioned above.The first part of this study recruited patients with non-metastatic primary right-sided colon cancer who underwent laparoscopic right hemicolectomy in one single center to compare the short-term and long-term outcomes of CME and D2 surgery.The primary endpoint of the study was the 3-year disease-free survival(DFS).The second part of this study focused on mid-transverse colon cancer,which showed some particularities in right-sided colon cancer.This part recruited patients with mid-transverse colon cancer who received radical laparoscopic surgery in one single center.The short-term and long-term outcomes of transverse colon colectomy versus hemicolectomy were compared.The primary endpoint of this part was 3-year DFS.The third part of this study recruited patients in the RELARC trial who accomplished laparoscopic right hemicolectomy and compared the safety and efficacy of intracorporeal with extracorporeal anastomosis.The primary endpoint was the incidence of abdominal infection.In this study,Kaplan-Meier curve and log-rank test was applied to compare the survival between different groups.COX multivariate regression analysis was used to verify the independent risk factors of survival.PSM(Propensity Score Matching)and IPTW(Inverse Probability of Treatment Weighting)was used in the third part to adjust associated confounders.Results:The first part included 314 patients,with 116 patients in CME group and 198 patients in D2 group.The mean operation time of CME surgery was longer than that of D2 surgery(158.7±41.1 VS 148.0±37.4 min,P=0.028)and the incidence of postoperative Clavien-Dindo-I(CD-I)complications occurred more frequently in CME group(11.2%VS 4.0%,P=0.014).The total number of lymph nodes harvested in the CME group was significantly more than that in the D2 group(35.7±15.3 VS 30.3±13.5,P=0.002),but there was no significant difference in 3-year DFS between the two groups(CME group:84.4%,95%CI 78.0%-91.3%VS D2 group:86.6%,95%CI 82.0%-91.5%,P=0.563).In the second part,70 patients were enrolled,among them,40 patients underwent transverse colectomy and 30 patients underwent right/left hemicolectomy.The overall postoperative complications were less(20.0%VS 40.0%,P=0.067)and the length of postoperative hospital stay was shorter(7d VS 7d,P=0.060)in the transverse colectomy group although without statistical significance.The 3-year DFS was comparable in the two groups(transverse colectomy:89.7%,95%CI 80.7%-99.8%VS right/left hemicolectomy:89.9%,95%CI 79.6%-100.0%,P=0.688).The long-term functional outcomes showed that the alternating regularities of defecation occurred more frequently in hemicolectomy group(51.7%VS 80.0%,P=0.030).The total number of lymph nodes harvested in the caudal-to-cephalic approach was significantly more than that of the cephalic-to-caudal approach in transverse colectomy(23.1 ±14.3 vs 13.4±5.4,P=0.004).Of the 975 patients enrolled in the third part,119 patients underwent intracorporeal anastomosis(ICA)and 856 patients underwent extracorporeal anastomosis(ECA).The ICA group was more likely to increase abdominal infection(9.2%VS 1.5%,IPTW:RR=5.7,95%CI 2.6-12.6,P<0.001)and wound infection(14.3%VS 3.3%,IPTW:RR=5.0,95%CI 2.9-8.6,P<0.001).The length of postoperative hospital stay was significantly longer in ICA group(8 vs 7 days,IPTW:HR=1.6,95%CI 1.3-1.9,P=0.004).In the ICA group,comparing with choosing another incision,choosing to lengthening the main port site to remove the specimen increased the risk of wound infection(17.3%VS 7.9%,P=0.172).Conclusions:Laparoscopic right hemicolectomy CME surgery did not show a significant long-term survival advantage compared with D2 surgery in the overall population and the overall complications after CME surgery appeared to occur more frequently than D2 surgery.For mid-transverse colon cancer,the oncological outcomes of laparoscopic transverse colectomy with D3 lymphadenectomy was comparable with right/left hemicolectomy and transverse colectomy was likely to reduce postoperative complications.The caudal-to-cephalic approach of transverse colectomy has advantages in completely removal of localized lymph nodes.Compared with the ECA group,the ICA group may increase the incidence of abdominal infection and wound infection.Choosing to lengthening the main port site may further increase the risk of wound infection in ICA group.The ICA group may prolong the length of postoperative hospital stay.