Short Term Postoperative and Oncological Outcomes of Two-Dimensional Versus Three-Dimensional Laparoscopic Transanal Total Mesorectal Excision of Rectal Cancer

Introduction

Three-dimensional (3D) laparoscopic surgery offers better spatial and depth perception ¹ compared to two-dimensional (2D) laparoscopic surgery. The immersive aspect of 3D laparoscopy improves focus. ² As a result, surgeons feel safer and more efficacious when they use a 3D system. ³ A systematic review has shown that 3D laparoscopy for abdominal surgery has reduced operative times and lower error rates compared to 2D laparoscopy. ⁴

With regard to rectal cancer, 3D laparoscopic resection is as safe and effective as 2D laparoscopy, ⁵ with added advantages of shorter operative times and a lower rate of conversion to laparotomy. ⁵ In the last decade, transanal total mesorectal excision (TaTME) is rapidly becoming recognized ⁶ for having advantages^7,8 over conventional laparoscopy, especially for rectal cancer patients who have a higher body mass index (BMI) or who have a narrow pelvis. ⁸

Given the benefits of 3D laparoscopic resection of rectal cancer, it stands to reason that similar benefits may be seen with the use of 3D with TaTME. Especially in TaTME, the added depth perception may confer advantage to surgeons who find this complex surgery challenging. We aim to evaluate the impact of 2D versus 3D laparoscopic TaTME on the treatment of rectal cancer.

Materials and Methods

A retrospective review of all patients with only rectal cancers who underwent TaTME in three centers in Singapore was conducted. Operative, Postoperative, and oncological outcomes of 2D versus 3D TaTME were examined and compared. Exclusion criteria included patients who underwent high anterior resection, use of TaTME as a bailout procedure, patients with incomplete data, and patients with benign disease.

The reason for exclusion of patients with high anterior resection is because TaTME is not routinely indicated in the treatment for rectal cancer. TaTME is only used in clinically challenging situations like higher BMI patients and narrow pelvis in males. We aim to look at oncological benefit for 3D versus 2D; hence, benign cases are excluded as well.

A total of 40 patients in the study period from October 2015 to August 2018 were included for analysis. Cases were recorded in a chronological and quasi-randomized manner. All patients underwent either ultralow anterior resection (total proctectomy with coloanal anastomosis) or low anterior resection (partial proctectomy with colorectal anastomosis below the anterior peritoneal reflection of the rectum).

Tumor location was defined by the relationship to the valves of Houston. Low and mid rectal tumors were located inferior to the proximal valve of Houston, and high rectal tumors were located superior to the proximal valve of Houston. Tumor distance from the anal verge was measured using magnetic resonance imaging scans.

In terms of completeness of mesorectal excision, Quirke's classification ⁹ was used. Incomplete (Grade 1) refers to resection in the muscularis propria plane. The resected specimen has exposed muscularis propria, moderate to marked coning, and irregular circumferential resection margin (CRM) on transverse sections. Nearly complete (Grade 2) refers to resection in the intramesorectal plane. There is moderate bulk to the mesorectum, one or more defects greater than 5 mm deep within the mesorectum, moderate coning, and irregular CRM on transverse sections but no visible muscularis propria. Complete (Grade 3) refers to resection in the mesorectal plane. The resected specimen has intact mesorectum with only minor irregularities, no defects deeper than 5 mm, no coning toward the distal margin of the resection specimen, and smooth CRM on transverse sections.

Anastomotic leaks were defined by the presence of clinical early or delayed leak, subclinical radiological leak, pelvic abscess, or anastomotic fistula.

The 3D system used in all 3D cases was the Olympus Flexible Tip™ 10 mm scope.

Univariate analysis comparing categorical variables was performed using the Pearson X² test, and continuous variables were analyzed using unpaired Student's t test. The Mann–Whitney U test was used for continuous variables that were not normally distributed. The Statistical Package for Social Sciences (SPSS) of IBM Statistics, version 20, was used for the statistical analysis.

This study was approved by and met the guidelines of our Domain Specific Review Board (DSRB).

Results

The demographics are shown in Table 1. It shows that the two groups of patients are very similar in terms of their baseline characteristics—gender, age, BMI, tumor site, tumor T stage, neoadjuvant chemoradiotherapy received, and type of surgery undergone. The cohort consists of mainly male patients (62.5%). A majority received neoadjuvant chemoradiotherapy (82.5%). Most had locally advanced tumors, that is, stage T3 and above (72.5%). All patients had a defunctioning ileostomy.

The operative outcomes are shown in Table 2. The main significant finding is that of a shorter operative time for the 3D group (340 versus 419 minutes, P = .04). There were no significant differences between the two groups concerning blood loss, postoperative complications such as surgical site infection and anastomotic leak, or length of hospital stay. None of the patients had conversion to open surgery. There were no operative deaths in either group.

In terms of oncological outcomes, Table 3 shows that there were no significant differences between the two groups concerning the length of margins, number of lymph nodes harvested, TME grade, or resection grade. Notably, complete TME grade 3 and R0 resection was achieved in all 23 patients in the 3D group, whereas the 2D group had 2 patients with nearly complete TME grade 2 and 1 patient with R1 resection, although this is not statistically significant.

Discussion

Since the first 3D laparoscopy was described by Becker et al, ¹⁰ there has been a slow uptake of 3D technology due to higher cost, the advent of robotic surgery in a similar decade, and a lack of strong evidence for its routine use. Although the differences between 2D and 3D systems were not recognized shortly after 3D systems were introduced, ¹¹ as technology improves, recent studies in various surgical disciplines have shown that 3D laparoscopic surgery has advantages such as shorter operative time and less blood loss.

Three-dimensional systems are of particular benefit for less experienced surgeons owing to shortened learning curves, as Nagendran et al. showed in their Cochrane review. ¹² Fanfani et al's ¹³ clinical trial randomized 90 endometrial and cervical cancer patients to 2D versus 3D laparoscopic hysterectomy and pelvic lymphadenectomy and showed that for 3D laparoscopy, there was a significantly shorter operative time for novice (<10 procedures) surgeons and significantly lower blood loss during lymphadenectomy. Gurusamy et al. ¹⁴ found in a Cochrane review that there were no differences between 3D versus 2D laparoscopic cholecystectomy in terms of postoperative complications, conversions, or operative times. However, the trial in this review was at high risk of bias. Subsequently, Bilgen et al. ¹⁵ showed that 3D imaging shortens the operative time for laparoscopic cholecystectomy.

Our study consists of 3 senior surgeons who had each performed more than 200 laparoscopic colorectal cancer surgeries. Many expert surgeons still find TaTME challenging to learn. This could be the reason why the superior 3D imaging allowing greater ease of plane recognition proved to be useful and led to a significantly shorter operative time. This is in accordance with a 2017 case-matched study by QingMin Zeng et al. ⁵ that evaluated short-term outcomes of 3D versus 2D laparoscopic radical resection of rectal cancer, which found that patients in the 3D group had shorter operative times and a lower rate of conversion to laparotomy.

In terms of oncological outcomes, all patients in the 3D TaTME group had R0 resection. Of note, there were several stage T4 patients in the 3D TaTME group. The ability to achieve R0 resection has been previously reported in our video article ¹⁶ and could be a result of the good spatial and depth perception offered by the 3D Olympus system.

Finally, our study demonstrates the safety of TaTME in an Asian cohort. TaTME has been contentiously debated to have a higher complication rate than standard laparoscopic TME. In our Asian cohort, patients who undergo TaTME have narrower pelvises. Of the patients in our study, 27.5% were overweight (BMI ≥23 by Asian standards), 62.5% were male, and all patients had a low or ultralow anterior resection. All these factors make dissection in the pelvis challenging.

Despite the above factors, we demonstrated a reasonable leak rate (including two subclinical leaks) of 10%. This is lower than the recent study by Penna et al. in Annals of surgery 2018 that reported an overall 15.7% ¹⁷ anastomotic leak rate in 1594 patients across 29 countries who underwent TaTME. Furthermore, we had no conversions to open surgery. This is significant compared to laparoscopic TME, which has conversion rates as high as 34%. ⁸ Such conversions are linked to increased morbidity and worse oncological outcomes. ⁸

There are a few limitations of this study. First, larger cohort studies are needed to investigate whether 3D laparoscopic TaTME provides any oncological benefit. Second, this is not a randomized trial. However, a pragmatic analysis of the available technology that could enhance the learning curve of experienced surgeons was made. Selection bias is inevitable, but confounders that are relevant to the study have been measured and a specific subgroup was selected to exclude most confounders.

Finally, the surgeons performing this technique are on their learning curve for TaTME and hence may not present a complete view on the potential of the use of 3D laparoscopy. Upon mounting the learning curve and becoming more familiar with TaTME technique, perhaps 3D TaTME would cease to be of significant benefit. Notwithstanding, 3D laparoscopy in TaTME has proven to be useful for experienced surgeons who embark on TaTME.

Conclusion

Our study demonstrated some key findings. First, TaTME is a safe technique with similar complication rates as laparoscopic TME. Second, the use of 3D laparoscopy for TaTME has the advantage of shorter operative time. Areas for further study include the cost effectiveness and functional and quality of life outcomes of 3D TaTME.