In 2011, Tuech et al described the first case of TaTME-SPLS in the world.[28] Then, Dumont et al presented 2 case reports in 2012.[29] Later on, TaTME-SPLS case reports were presented by 2 teams in 2013 and 2015.[30, 31] 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).
After the first single-port laparoscopic right hemi-colectomy had been described in 2008,[32] 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.[33, 34] 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.[35] 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.[35] 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).[36, 37] The splenic flexure must be mobilized for the descending colon to reach the deep pelvis for the anastomosis.[36, 37] 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.[38, 39] In effect, mobilization of the splenic flexure was mainly performed in patients with a short left mesentery.[40] 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.[41-43] 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.[44, 45],[46] 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 (Table 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.[47-49] According to previous studies, better pathologic complete response rate after neoadjuvant CCRT was associated with superior survival outcomes.[47, 48, 50-52] 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.[51, 52] 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.[51, 52]
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.[44, 45] Patient-volume for surgeons familiar with neoadjuvant CCRT followed by TaTME-SPLS might be concerned.