Endoscopic treatments for rectal neuroendocrine tumors smaller than 16 mm: a meta-analysis

Objective: Endoscopic mucosal resection (EMR), including conventional EMR (c-EMR) and modified EMR (m-EMR), was applied to remove small rectal neuroendocrine tumors (NETs). We aim to evaluate treatment outcomes of endoscopic submucosal dissection (ESD), m-EMR and c-EMR for rectal NETs <16 mm. Methods: The PubMed, Cochrane Library and Elsevier Science Direct were searched to identify eligible articles. After quality assessment and data extraction, meta-analysis was performed. The main outcomes were complete resection rate, overall complication rate, procedure time and local recurrence rate. Results: Compared with c-EMR, ESD could achieve higher complete resection rate (OR = 4.38, 95%CI: 2.43–7.91, p < 0.00001) without increasing overall complication rates (OR = 2.21, 95%CI: 0.56–8.70, p = 0.25). However, ESD was more time-consuming than c-EMR (MD = 6.72, 95%CI: 5.84–7.60, p < 0.00001). Compared with m-EMR, ESD did not differ from m-EMR in complete resection and overall complication rates (OR = 0.80, 95%CI: 0.51–1.27, p = 0.34; OR = 1.91, 95%CI: 0.75–4.86, p = 0.18, respectively). However, ESD was more time-consuming than m-EMR (MD = 12.21, 95%CI: 7.78–16.64, p < 0.00001). Compared with c-EMR, m-EMR could achieve higher complete resection rate (OR = 4.23, 95%CI: 2.39–7.50, p < 0.00001) without increasing overall complication rate (OR = 1.07, 95%CI: 0.35–3.32, p = 0.90). Moreover, m-EMR was not time-consuming than c-EMR (MD = 2.01, 95%CI: −0.37–4.40, p= 0.10). The local recurrence rate was 0.84% (9/1067) during follow-up. Conclusions: Both ESD and m-EMR have great advantages over c-EMR in complete resection rate without increasing safety concern while m-EMR shares similar outcomes with ESD for rectal NETs <16 mm. The results should be confirmed by well-designed, multicenter, randomized controlled trials with large samples and long-term follow-ups from more countries.