Can transanal endoscopic microsurgery effectively treat T1 or T2 rectal cancer?A systematic review and meta-analysis.

[AIM] We aimed to compare the safety and oncological outcomes of transanal endoscopic microsurgery (TEM) and radical surgery (RS) for patients with T1 or T2 rectal cancer.

[METHOD] We searched Pubmed, Embase, Cochrane Library databases for relevant studies comparing TEM with RS in rectal cancer published until April 2020. We focused on safety and oncological outcomes.

[RESULTS] This meta-analysis included 3526 patients from 12 studies. Compared with RS, TEM had a shorter operative time (weighted mean difference [WMD] -110.02, 95% confidence interval [CI]: 143.98, -76.06), less intraoperative blood loss (WMD -493.63, 95% CI: 772.66, -214.59), lower perioperative morality (risk ratio [RR] 0.25, 95% CI: 0.06, 0.99), and fewer postoperative surgical complications (RR 0.23, 95% CI: 0.11,0.45). TEM was associated with more patients with a positive margin or a doubtfully complete margin than RS (RR 7.36, 95% CI: 3.66, 14.78). TEM was associated with higher local recurrence (RR 2.63, 95% CI: 1.60, 4.31) and overall recurrence (RR 1.60, 95% CI: 1.09, 2.36). TEM had a negative effect on 5-year overall survival (hazard ratio [HR] 1.51, 95% CI: 1.16, 1.96), especially in the T2 without neoadjuvant therapy (NAT) subgroup (HR 2.02, 95% CI: 1.32, 3.09), but in the subgroups of T1 or T2 with NAT before TEM, TEM did not yield a significantly lower overall survival than RS.

[CONCLUSION] TEM seems appropriate for T1 rectal cancer with favourable histopathology. For patients with T2 rectal cancer, NAT before TEM may contribute to achieving oncological outcomes equivalent to that achieved with RS.