Complete Histologic Resection of Adenomatous Polyps?
Condition: Adenomatous Polyps
MeSH terms: Adenomatous Polyps; Polyps
Study type: Observational

Summary: 
      Colorectal cancer is the second most common cause of cancer death in the US. Colonoscopy is
      considered the best test colorectal cancer screening. It allows resection of adenomatous
      polyps (a known cancer precursor) and thus, interrupt the adenoma-carcinoma sequence. Despite
      the potential benefit of screening colonoscopy recent studies have reported cases of
      colorectal cancers in a short interval after prior screening or surveillance colonoscopies.
      One possible cause of such interval cancers may be incomplete resection of adenomatous polyps
      and hence ongoing growth and cancer development in such lesions. Complete resection may be
      particularly important for polyps of at least 5mm in size as up 10% of such polyps higher
      risk lesions as villous adenoma, tubulovillous adenoma, high grade dysplasia, or early
      carcinoma.

      Although adenoma resection of sessile and flat adenomatous polyps between 5 and 20mm is
      believed to be well standardized data on complete resection of adenomatous tissue are sparse.
      This may be related to the assumption that using a snare with electro-cautery will
      successfully remove the polyp and cauterize remaining marginal adenomatous tissue and hence
      completely remove and or destroy the lesion.

      The investigators are interested in examining how often sessile adenomatous polyps between 5
      and 20mm are completely removed using standard polypectomy snare. The investigation was also
      directed at a comparison between complete resection of polyps between 5 and 9mm and 10 and
      20mm.
    

Detailed description: 
      All patients who present for a colonoscopy and meet inclusion and exclusion criteria will be
      asked to participate, and all patients with resectable polyps will be included. See also
      inclusion and exclusion criteria.

      All patients will have undergone a regular bowel preparation with polyethylene glycol lavage
      with 4-6 L until clear rectal fluid is evacuated.

      Polyp resection will be performed by experienced endoscopists (each with over 500
      colonoscopies performed). All polyps between 5 and 20mm will be removed with an
      electro-cautery snare. Polyp size will be estimated using the snare catheter (2.5mm) or the
      snare diameter (10x20mm, 15x30mm, 20x20mm) before resection. The endoscopist will grade the
      difficulty of resection. Following the resection, the endoscopist will closely examine the
      resection margins. Biopsies will be taken from resection margins: 2 biopsies will be obtained
      from opposite margins for polyps 5-9mm, and 4 biopsies will be taken for polyps 10-20mm from
      all four quadrants of the resection margins. In case of assumed incomplete resection this
      will be documented and further (piecemeal) resections should be done, if this is not
      feasible, margins can be cauterized according to standard polypectomy resection (e.g. by
      argon beamer coagulation) after previous biopsy. Only those polyps that are found to be
      adenomatous polyps will be included in the analysis.

      If polyp resection is complicated by bleeding (not self-sustained), no biopsies will be taken
      and any additional polyps that will be found during the remaining examination will be
      excluded from analysis. Any bleeding from the margins after polypectomy will be treated by
      endoscopic injection using diluted epinephrine (1:10.000).

      A single research subject may have many eligible polyps. To avoid taking many biopsies, the
      investigators will not include more than 5 eligible polyps (the first 5 that are detected)
      per patient in the study.

      Laboratory Analysis:

      Polyps and biopsies will be sent to the pathology lab of each center. The polyps will be
      evaluated according to common practice. In addition information regarding resection margins
      will be provided for each polyp: R0= free of adenomatous tissue, R1=adenomatous tissue
      detected in the margin. This information is not routinely provided by the pathologist as
      there is so far no data whether this information is reliable. Only adenomatous polyps will be
      included in the analysis. Hyperplastic polyps will not be included. Biopsies will only be
      processed after the diagnosis of an adenomatous polyp was made. Biopsies will be evaluated
      for presence of adenomatous tissue. The additional impact for the pathology lab includes a)
      processing of biopsies belonging to the polyp specimens, and b) providing information on
      polyp margins. The VA pathology lab estimated the financial impact to be low and there will
      be no financial requests. The pathological diagnosis, including the reading of the biopsies,
      will become part of the medical record. If biopsies contain adenomatous tissue the patient
      will be ask to return for a follow-up colonoscopy within 1 year. This is within current
      standard of care to repeat a colonoscopy to assure complete adenoma resection.
    

Intervention name(s): standard polypectomy snare
Intervention type(s): Other
Intervention description(s): Electrocautery snare resection of sessile colonic polyps
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Participants eligible for recruitment are patients who present for a colonoscopy to the
        VAMC or DHMC Gastroenterology department conducting this study. Upon arrival for a
        scheduled colonoscopy patient records will be reviewed to determine eligibility.
      
Biospecimen description: 
      Biopsies will be taken from resection margins: 2 biopsies will be obtained from opposite
      margins for polyps 5-9mm, and 4 biopsies will be taken for polyps 10-20mm from all four
      quadrants of the resection margins.
    
Keywords: colon polyps; adenoma resection; colon cancer screening; colonoscopy