Transanal endoscopic microsurgery for T1 and T2 rectal cancers: a meta-analysis and meta-regression analysis of outcomes.

The objective of this study is to assess transanal endoscopic microsurgery (TEM) as a surgical strategy for stage I rectal cancer. The literature lacks level I and level II evidence of the oncologic competence of TEM. Three randomized controlled, one prospective, and seven retrospective comparative studies were evaluated. End-points included perioperative outcomes, margin involvement, disease-free and overall survival, and recurrence. The number of patients with major (odds ratio (OR) = 0.24, 95% confidence interval (CI) 0.07-0.91) and overall postoperative complications (OR = 0.16, 95% CI 0.06-0.38) were significantly lower in TEM. The disease-free survival was higher in standard resection (SR) group compared with TEM (OR = 0.46, 95% CI 0.24-0.88). The number of patients with positive margins were less in the SR group (OR = 6.49, 95% CI 1.49-24.91), which was associated with lower local recurrence (OR = 4.92, 95% CI 1.81-13.41) and overall recurrence rate (OR = 2.03, 95% CI 1.15-3.57). No survival advantage was observed in favor of either procedure. TEM had lower rate of positive margins and longer disease-free survival when compared with transanal excision (TAE). TEM seems to be superior to SR concerning morbidity whilst less effective in obtaining negative surgical margins, and it is associated with higher local and overall recurrence. No survival advantage was observed in favor of either procedure. Unfavorable tumor preoperative histology does not seem to influence the selection between TEM and SR. TEM is more effective than TAE in obtaining negative surgical margins and shows a greater disease-free survival.