Does Cap Assisted Colonoscopy Improve Detection of Adenomatous Polyps? (CAP Trial)
Condition: Adenomatous Polyps
MeSH terms: Adenomatous Polyps; Polyps
Study type: Interventional

Summary: 
      Effectiveness of screening colonoscopy in cancer prevention relies on the detection and
      removal of adenomatous polyps. However, a substantial rate of adenomas is missed during a
      colonoscopy. It has been estimated that two thirds of missed adenomas are located on the
      proximal aspect of colonic folds. Attaching a transparent cap to the tip of a colonoscope may
      allow examination of the proximal aspect of colonic folds, and some early studies have
      suggested an increased polyp and adenoma detection using this technology. However, the
      studies have in part substantial methodological limitations (e.g. missing polyp histology,
      single endoscopist study, polyps not removed at the time of detection). Therefore, at this
      point it is unclear whether cap assisted colonoscopy may improve adenoma detection. The
      objective of this study is to evaluate whether cap assisted colonoscopy improves adenoma
      detection.

      The investigators propose a two-center multiple endoscopists randomized controlled trial.
      Patients will be randomized to cap assisted colonoscopy or standard high definition white
      light colonoscopy. The cap is a 4mm commercially available transparent cap that is attached
      to the tip of the colonoscopy. Primary outcome measure is the adenoma detection rate (mean
      number of adenoma per patient). The investigators will assess and adjust for possible
      variables that can affect adenoma detection, including withdrawal time and quality of colon
      preparation. As a secondary outcome of interest the investigators will evaluate a possible
      learning curve effect among all endoscopists (a minimum of six) new to this method. In
      addition the investigators will evaluate whether cap assisted endoscopy improves real time
      prediction of polyp histology.
    

Detailed description: 
      All patients who present for a colonoscopy and meet inclusion and exclusion criteria will be
      asked to participate (see inclusion and exclusion criteria). All patients will undergo a
      regular bowel preparation with polyethylene glycol lavage (based on current standard of care)
      until clear rectal fluid is evacuated. Patients will be randomized to one of two groups:

        1. Standard colonoscopy, or

        2. Cap assisted colonoscopy. All colonoscopies will be performed using state of the art
           high-definition wide angle colonoscopy. The transparent cap, which is attached to the
           tip of the colonoscope, has a 4mm margin extending beyond the tip of the colonoscope.
           All patients will undergo a careful endoscopic examination. A timer will provide
           feedback on the time of insertion and the withdrawal time. Detected polyps will be
           assessed with standard white light and narrow band imaging to predict polyp histology
           (adenoma versus no adenoma), then resected and sent for histological evaluation
           according to standard of care. At least 8 experienced endoscopists at the participating
           centers will participate. Each endoscopist will perform at least 50 cap assisted
           colonoscopies as part of the study. Each endoscopist will be asked to complete a survey
           after 10 and after 50 cap assisted colonoscopies.

      Patients will be randomized in blocks of four allocated to each examiner. The order of
      randomization will be computer generated. Information on randomization will be contained in
      sealed envelopes assigned to each examiner and individually opened immediately before the
      procedure after a patient's All participating endoscopist will fill out a questionnaire
      regarding the use of cap assistance colonoscopy after the initial 10 cap assisted
      colonoscopies and after at least 50 cap assisted cap colonoscopies. Endoscopists will also
      undergo a training session with respect to real time polyp diagnosis before study
      commencement and after each 20 colonoscopies enrollment.
    

Intervention name(s): Colonoscopy Cap
Intervention type(s): Device
Intervention description(s): 4mm transparent cap (Olympus) mounted to the tip of a colonoscope.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Screening
Keywords: colon polyps; adenoma resection; colon cancer screening; colonoscopy; polyp detection