Comparison of transanal endoscopic microsurgery with or without neoadjuvant therapy and standard total mesorectal excision in the treatment of clinical T2 low rectal cancer: a meta-analysis

Some clinical trials demonstrated local resection for clinical T1 rectal cancer was safe and effective. But for clinical T2 rectal cancer, the results were controversial. Neoadjuvant therapy (NT) is proven to reduce the opportunity of advanced rectal cancer recurrence in various researches. The objective of this Meta-Analysis was to evaluate the oncological outcomes of transanal endoscopic microsurgery (TEM) with or without NT comparing with conventional total mesorectal excision (TME) for the treatment of clinical T2 rectal cancer.To search for the relevant studies, an electronic search was done from the databases of Pubmed, Embase, and the Cochrane Library in this meta-analysis. We compared the effectiveness of transanal endoscopic microsurgery with or without NT and standard total mesorectal excision in the treatment of T2 Rectal Cancer. 1RCT and 3nRCTs including 121 TEM patients (TEM + NT: 59, TEM: 62) and 174 TME patients with T2 rectal cancer were retrieved. Compared with TME, there were no significant differences in the outcomes of local recurrence, overall recurrence, overall survival between TEM + NT group. However in compassion with TME, TEM without NT was associated with an increased local recurrence, overall recurrence, and a shorter overall survival, with individual ORs being 3.04 (95% Cl: 1.17-7.90; I2 = 0%), 5.67 (95% Cl: 1.58-20.38; I2 = 0%) and 0.12 (95% Cl: 0.02-0.65; I2 = 0%), respectively. Compared with TME, TEM after NT may be a feasible and safe organ preservative approach for patients with clinical T2 low rectal cancer. But for those without NT, TEM always seem be associated with worse oncological outcomes.