Transanal total mesorectal excision for locally advanced middle-low rectal cancers

A systematic review and meta-analysis of robotic-assisted transabdominal total mesorectal excision and transanal total mesorectal excision: which approach offers optimal short-term outcomes for mid-to-low rectal adenocarcinoma?

BACKGROUND

Resection of low rectal adenocarcinoma can be challenging in the narrow pelvis of male patients. Transanal total mesorectal excision (TaTME) appears to offer technical advantages for distal rectal tumours, and robotic-assisted transabdominal TME (rTME) was introduced in effort to improve operative precision and ergonomics. However, no study has comprehensively compared these approaches. The aim of the present study was to perform a systematic review of the literature to compare postoperative short-term outcomes in rTME and TaTME.

METHODS

A systematic online search (1974-July 2020) of MEDLINE, Embase, web of science and google scholar was conducted for trials, prospective or retrospective studies involving rTME, or TaTME for rectal cancer. Outcome variables included: hospital stay; operation duration, blood loss; resection margins; proportion of histologically complete resected specimens; lymph nodes; overall complications; anastomotic leak, and 30-day mortality.

RESULTS

Sixty-two articles met the inclusion criteria, including 37 studies (3835 patients) assessing rTME resection, 23 studies (1326 patients) involving TaTME and 2 comparing both (165 patients). Operating time was longer in rTME (309.2 min, 95% CI 285.5-332.8) than in TaTME studies (256.2 min, 95% CI 231.5-280.9) (p = 0.002). rTME resected specimens had a larger distal resection margin (2.62 cm, 95% CI 2.35-2.88) than in TaTME studies (2.10 cm, 95% CI 1.83-2.36) (p = 0.007). Other outcome variables did not significantly differ between the two techniques.

CONCLUSIONS

rTME provides similar pathological and short-term outcomes to TaTME and both are reasonable surgical approaches for patients with mid-to-low rectal cancer. To definitively answer the question of the optimal TME technique, we suggest a prospective trial comparing both techniques assessing long-term survival as a primary outcome.

Statistical, Clinical, Methodological Evaluation of Local Recurrence Following Transanal Total Mesorectal Excision for Rectal Cancer: A Systematic Review

BACKGROUND

A recent Norwegian moratorium challenged the status quo of transanal total mesorectal excision for rectal cancer by reporting increased early multifocal local recurrences.

OBJECTIVE

The aim of this systematic review and meta-analysis was to evaluate the local recurrence rates following transanal total mesorectal excision as well as to assess statistical, clinical, and methodological bias in reports published to date.

DATA SOURCES

The PubMed and MEDLINE (via Ovid) databases were systematically searched.

STUDY SELECTION

Descriptive or comparative studies reporting rates of local recurrence at a median follow-up of 6 months (or more) after transanal total mesorectal excision were included.

INTERVENTIONS

Patients underwent transanal total mesorectal excision.

MAIN OUTCOME MEASURES

Local recurrence was any recurrence located in the pelvic surgery site. The untransformed proportion method of 1-arm meta-analysis was utilized. Untransformed percent proportion with 95% confidence interval was reported. Ad hoc meta-regression with the Omnibus test was utilized to assess risk factors for local recurrence. Among-study heterogeneity was evaluated: statistically by I2 and τ2, clinically by summary tables, and methodologically by a 33-item questionnaire.

RESULTS

Twenty-nine studies totaling 2906 patients were included. The pooled rate of local recurrence was 3.4% (2.7%-4.0%) at an average of 20.1 months with low statistical heterogeneity (I2 = 0%). Meta-regression yielded no correlation between complete total mesorectal excision quality (p = 0.855), circumferential resection margin (p = 0.268), distal margin (p = 0.886), and local recurrence rates. Clinical heterogeneity was substantial. Methodological heterogeneity was linked to the excitement of novelty, loss aversion, reactivity to criticism, indication for transanal total mesorectal excision, nonprobability sampling, circular reasoning, misclassification, inadequate follow-up, reporting bias, conflict of interest, and self-licensing.

LIMITATIONS

The studies included had an observational design and limited sample and follow-up.

CONCLUSION

This systematic review found a pooled rate of local recurrence of 3.4% at 20 months. However, given the substantial clinical and methodological heterogeneity across the studies, the evidence for or against transanal total mesorectal excision is inconclusive at this time.

Controversies and consensus in transanal total mesorectal excision (taTME): Is it a valid choice for rectal cancer?

Transanal total mesorectal excision (taTME) is a novel approach to radical surgery for low rectal cancer. taTME is associated with the benefits of a higher rate of free distal resection margins (DRM) under direct visualization, better visualization of the mesorectal plane, and the feasibility of overcoming the restriction of the distal pelvis. Thus, it is increasingly used globally. In this review, we investigated whether taTME yields better short- and long-term outcomes than laparoscopic TME.