In 2011, Tuech et al described the first case of TaTME-SPLS in the world.[27] Then, Dumont et al presented 2 case reports in 2012.[28] Later on, TaTME-SPLS case reports were presented by 2 teams in 2013 and 2015.[29, 30] Until 2017, Meillat et al had published the first retrospective study of 41 patients who underwent TaTME-SPLS, rather than cases reports.[18] Our study will be the second retrospective study for TaTME-SPLS in the world and the first retrospective study of neoadjuvant CCRT followed by TaTME-SPLS in Asian patients with middle to lower third rectal adenocarcinoma (within 8 cm from anal verge measured by rigid sigmoidoscopy based on our previous studies).[19–22] Meillat et al revealed a low conversion rate (2%), high sphincter preservation rate (100%), and an acceptable 30-day morbidity rate (24%) in 41 patients.[18] In comparison with the previous study, our study had similar results for age, BMI, tumor location, operative time, location of ileostomy, conversion rate, 30-day complication rate, 30-day mortality rate, number of lymph nodes harvested, and length of hospital stay (Table 3). However, we had a higher rate of neoadjuvant CCRT (100%), mobilization of the splenic flexure (65.22%), ISR (60.87%), stapled types of anastomosis (39.13%), and better pathologic response with downstaging in our study (Table 3).
The present study also had a low conversion rate (4.35%), high sphincter preservation rate (100%), an acceptable 30-day morbidity rate (21%) and no 30-day mortality. In the present study, no significant difference was observed in conversion rate, BMI, organ preservation rate, mortality, and morbidity rate, compared with the study of Meillat et al.[18] However, percentages of patients receiving neoadjuvant CCRT in our study and the Meillat et al were 100% and approximately 70%, respectively. Traditionally, the conversion rates in previous laparoscopic rectal surgery studies were 10%-15%.[31–37] With the progression of radiotherapy techniques and laparoscopic rectal surgery, lower incidence of conversion rate (< 5%) among patients with middle to lower third rectal cancer undergoing TaTME-SPLS was observed in this and the Meillat et al study (Supplemental Table 1). Our study was the first to demonstrate that standard neoadjuvant CCRT will not increase the risk of conversion in patients with middle to lower third rectal cancer undergoing TaTME-SPLS. The toxicities of neoadjuvant CCRT followed by TaTME-SPLS seemed tolerable and acceptable in our study. The novelty of our study was neoadjuvant CCRT followed with TaTME-SPLS result in very high organ preservation rate (100% in our study) in middle to lower third rectal adenocarcinoma.
ISR was performed more frequently in our study than in that of Meillat et al (60.87% vs 36.59%). For a highly selective group of patients with low-lying rectal cancer, in whom the standard low anterior resection (LAR) would not yield an adequate distal margin, proctectomy with ISR can be a viable alternative to APR.[38, 39] In our study, we performed ISR in approximately 60% of patients receiving TaTME-SPLS because the tumor locations were close to dentate line of the anus. Compared with the Meillat et al study, our study might have had more low-lying rectal adenocarcinomas. However, the organ preservation rate and clean distal margin were still 100% in our study. These findings might imply neoadjuvant CCRT followed by TaTME-SPLS will be a good solution for low-lying rectal adenocarcinoma and can result into superior organ preservation (100%), clean distal margin (100%), and better pathologic response with downstaging. We made the anastomosis by transanal stapler in 40% patients, but Meillat et al reported that all of their patients had undergone colo-anal anastomosis by hand-sewn methods.[18] The ileal anal anastomosis was performed using the stapled or hand-sewn technique, depending upon the preference of the surgeon.[40, 41] In our hospital, staple technique is performed more frequently because of surgeons’ concern for possible inadequate margin during operation; staples can be a reference location of inadequate margin for radio-oncologists.
After the first single-port laparoscopic right hemi-colectomy had been described in 2008,[42] several studies suggested the benefits of single-port laparoscopic colectomy over multiple port laparoscopic surgery, which included better cosmetic outcomes, less postoperative pain, and faster postoperative recovery.[43, 44] Otherwise, reports that described TME-SPLS for rectal cancer were limited. A report by Tei et al in 2015 discussed short-term outcomes of TME-SPLS in 50 patients with rectal cancer.[45] Tei et al concluded that TME-SPLS is a safe and feasible procedure for selective patients with rectal cancer. The middle to lower third rectal cancer was excluded because of technical difficulty.[45] Although the advantages of single port colectomy still under investigation and might be associated little benefits, our patients want to try the single port colectomy in our hospital, because relatively small and less wound while using single port colectomy. At present, we might suggest that neoadjuvant CCRT followed by TaTME- SPLS may be the solution to TME-SPLS for low-lying rectal cancer with 100% organ preservation, 100% clean distal margin, and superior pathologic response.
LAR involves removal of the sigmoid colon and rectum to a level, where the distal margin is free of cancer, followed by a primary anastomosis between the descending colon and the rectum (colorectal anastomosis) or the anal sphincter (colo-anal anastomosis).[38, 39] The splenic flexure must be mobilized for the descending colon to reach the deep pelvis for the anastomosis.[38, 39] Previous studies indicated that mobilization of the splenic flexure was mandatory, to ensure an optimal blood supply to the residual colon and a tension-free anastomosis.[46, 47] In effect, mobilization of the splenic flexure was mainly performed in patients with a short left mesentery.[48] However, mobilization of the splenic flexure was not free from intra-operative complications, like the spleen injury, and it increased the complexity of an already demanding operation, such as rectal resection.[49–51] In addition, limitations to TaTME included the inability to completely visualize the intracoelomic cavity, transect the inferior mesenteric artery in an oncologic high ligation fashion, and mobilization of the splenic flexure.[15] Most experts have recommended it for female patients with benign disease without prior radiotherapy.[52, 53],[54] However, in our study, neoadjuvant CCRT followed by TaTME-SPLS was performed smoothly in all patients with middle to lower third rectal adenocarcinoma (from anal verge 0–8 cm measured by rigid sigmoidoscopy), including 82.61% patients, in whom mobilization of the splenic flexure was performed. Our findings imply that neoadjuvant CCRT did not increase difficulty and comorbidities in patients with low-lying rectal adenocarcinoma, receiving TaTME-SPLS (Table 3).
Patients with low-lying rectal adenocarcinoma (from anal verge 0–8 cm measured by rigid sigmoidoscopy), receiving TaTME-SPLS had better pathologic complete response rate and more downstaging of pathologic T and N stages, compared with the Meillat et al study (Tables 2 and 3). In our study, neoadjuvant CCRT might be contributing to better pathologic response and clean distal margin in all patients, compared with the Meillat et al study.[18] The pathologic complete response rate (21.74%) after neoadjuvant CCRT in this study was compatible with the previous studies.[55–57] According to previous studies, better pathologic complete response rate after neoadjuvant CCRT was associated with superior survival outcomes.[55, 56, 58–60] Our outcomes of neoadjuvant CCRT followed by TaTME-SPLS in patients with low-lying rectal cancer can be promising and might be compatible with previous studies; we need longer follow-up time to verify the better survival in our study.[59, 60] Our findings suggest that neoadjuvant CCRT followed by TaTME-SPLS in patients with low-lying rectal adenocarcinoma might bring in better organ preservation, clean distal margin, tolerable toxicities, and superior pathologic complete response with potential better overall survival.[59, 60]
This study had some strengths. Prior to this study, no clinical data had proven that neoadjuvant CCRT followed by TaTME-SPLS in patients with low-lying rectal adenocarcinoma leads to excellent organ preservation, clean distal margin, acceptable toxicities, and good pathologic complete response; this study provides novel data. Our definition of low-lying rectal adenocarcinoma was clear (from anal verge 0–8 cm), and measuring tools were consistent, that is, rigid sigmoidoscopy. Our regiments of neoadjuvant CCRT, interval from complete of CCRT to surgery, and procedures of TaTME-SPLS were consistent and without discrepancy treatments. Our study was the first study to evaluate the effect of neoadjuvant CCRT followed by TaTME-SPLS in patients with low-lying rectal adenocarcinoma. Additionally, this is also the first study that presents neoadjuvant CCRT followed by TaTME-SPLS as safe and effective for organ preservation without inadequate margin in Asian patients with low-lying rectal adenocarcinoma.
This study had some limitations. First, in this study, the sample size of patients with low-lying rectal adenocarcinoma who underwent neoadjuvant CCRT followed by TaTME-SPLS was small. Second, all patients with low-lying rectal adenocarcinoma were enrolled from an Asian population, and so, the corresponding ethnic susceptibility remains unclear. Therefore, our results must be cautiously extrapolated to non-Asian populations. Third, surgeons not familiar with this technique needed standardized training, including observations, cadaveric labs or hands-on courses, and proctorship or mentorship, with early case experiences.[52, 53] Patient-volume for surgeons familiar with neoadjuvant CCRT followed by TaTME-SPLS might be concerned.