Transanal minimally invasive surgery (TAMIS) versus endoscopic submucosal dissection (ESD) for resection of non-pedunculated rectal lesions (TRIASSIC study): study protocol of a European multicenter randomised controlled trial
Authors: Dekkers Nik , Boonstra Jurjen J. , Moons Leon M. G. , Hompes Roel , Bastiaansen Barbara A. , Tuynman Jurriaan B. , Koch Arjun D. , Weusten Bas L. A. M. , Pronk Apollo , Neijenhuis Peter A. , Westerterp Marinke , van den Hout Wilbert B. , Langers Alexandra M. J. , van der Kraan Jolein , Alkhalaf Alaa , Lai Jonathan Y. L. , ter Borg Frank , Fabry Hans , Halet Eric , Schwartz Matthijs P. , Nagengast Wouter B. , Straathof Jan Willem A. , ten Hove Rogier W. R. , Oterdoom Leendert H. , Hoff Christiaan , Belt Eric J Th , Zimmerman David D. E. , Hadithi Muhammed , Morreau Hans , de Cuba Erienne M. V. , Leijtens Jeroen W. A. , Vasen Hans F. A. , van Leerdam Monique E. , de Graaf Eelco J. R. , Doornebosch Pascal G. , Hardwick James C. H. 
Published: July 2020

Abstract
Background
In the recent years two innovative approaches have become available for minimally invasive en bloc resections of large non-pedunculated rectal lesions (polyps and early cancers). One is Transanal Minimally Invasive Surgery (TAMIS), the other is Endoscopic Submucosal Dissection (ESD). Both techniques are standard of care, but a direct randomised comparison is lacking. The choice between either of these procedures is dependent on local expertise or availability rather than evidence-based. The European Society for Endoscopy has recommended that a comparison between ESD and local surgical resection is needed to guide decision making for the optimal approach for the removal of large rectal lesions in Western countries. The aim of this study is to directly compare both procedures in a randomised setting with regard to effectiveness, safety and perceived patient burden.

Methods
Multicenter randomised trial in 15 hospitals in the Netherlands. Patients with non-pedunculated lesions > 2 cm, where the bulk of the lesion is below 15 cm from the anal verge, will be randomised between either a TAMIS or an ESD procedure. Lesions judged to be deeply invasive by an expert panel will be excluded. The primary endpoint is the cumulative local recurrence rate at follow-up rectoscopy at 12 months. Secondary endpoints are: 1) Radical (R0-) resection rate; 2) Perceived burden and quality of life; 3) Cost effectiveness at 12 months; 4) Surgical referral rate at 12 months; 5) Complication rate; 6) Local recurrence rate at 6 months. For this non-inferiority trial, the total sample size of 198 is based on an expected local recurrence rate of 3% in the ESD group, 6% in the TAMIS group and considering a difference of less than 6% to be non-inferior.

Discussion
This is the first European randomised controlled trial comparing the effectiveness and safety of TAMIS and ESD for the en bloc resection of large non-pedunculated rectal lesions. This is important as the detection rate of these adenomas is expected to further increase with the introduction of colorectal screening programs throughout Europe. This study will therefore support an optimal use of healthcare resources in the future.

Trial registration
Netherlands Trial Register, NL7083, 06 July 2018.