ESD and TAMIS: Results from a multicenter study

Rationale: Colorectal cancer (CRC) is the second most prevalent cancer in the Netherlands, with 15,000 new cases per year and 5000 colorectal cancer related deaths. The Dutch
National Colorectal Cancer screening program began in 2014 and is expected to save 1400 lives per year in the short term through early diagnosis and treatment of cancer. In the longer
term it is expected to save an additional 1000 lives per year through the prevention of cancer by removing advanced polyps. In the last few years two new highly promising innovative
approaches have become available for minimally invasive en bloc resection of large non-pedunculated rectal lesions. One is a new endoscopic technique called endoscopic
submucosal dissection (ESD) and the other is a new surgical technique called transanal minimally invasive surgery (TAMIS). Although both techniques are standard care in the
Netherlands, a randomized comparison between TAMIS and ESD is lacking. Therefore the TRIASSIC study (NL61603.058.18) was started; A multicenter, randomised controlled trial
comparing TAMIS and ESD for resection of non-pedunculated rectal lesions.This study will further increase knowledge on the preferred minimal invasive method by prospectively
collecting data of the patients refusing to be randomised in the TRIASSIC study.

Objective: The aim for this study is to assess the safety and effectiveness of both ESD and TAMIS in the rectum.

Study design: Prospective observational study

Study population: Patients eligible for inclusion for the TRIASSIC study, but refused randomization due to, for example, a distinct preference for one of the procedures. (Patients
18 years of age or older with a large non-pedunculated polyp in the rectum found during screening, surveillance of diagnostic colonoscopy)

Intervention: Resection will be performed using either the TAMIS technique or the ESD technique.

Main study parameters/endpoints: To improve our knowledge of the safety and effectiveness for both procedures by assessing: recurrence rate at follow-up colonoscopy at
6 and 12 months. Secondary endpoints: 1. Radical (R0-) resection rate 2. Surgical referral rate at 12 months 3. Complication rate.

Nature and extent of the burden and risks associated with participation, benefit and group relatedness: Both resection techniques investigated in this study are standard care in the Netherlands.
Therefore participating will not be associated with an increased risk compared to standard care. Certain procedures that are optional but recommended in standard care will be
performed in all participating patients, including (1) MRI of the rectum and (2) biopsies of the scar at follow-up rectoscopies. Follow-up rectoscopy is standard care after resection of an
adenoma and will be performed 6 and 12 months after resection. Taken together neither an unacceptable risk nor a direct benefit is expected for patients participating in this study.
Collecting prospective data from patients not willing to be randomized in the TRIASSIC study makes sure even more data will be collected on these relatively new minimal invasive
methods, with scarce prospective data in western population, increasing our knowledge on the preferred minimal invasive method. This is important as the detection rate of these
adenomas is expected to further increase with the introduction of the Dutch CRC screening program in 2014. Therefore this study will support an optimal use of healthcare resources in
the future.

We hypothesize that ESD will be associated with longer procedure times but lower costs. For lesions that prove to be benign, we hypothesize that ESD will lead to a higher number of R0 resections and lower recurrence rates, particularly for lesions involving the dentate line, and less serious complications than TAMIS. For lesions that prove to be invasive we hypothesize that TAMIS will have a higher R0 resection rate but that this will not translate to a reduced need for additional surgery.

The primary outcome (recurrent polyp) is measured after 6 months and 12 months by endoscopy

In this observational side study of the TRIASSIC trial patients will either undergo resection by the TAMIS technique or by the ESD technique.