title: Colonoscopic findings and tumor site do not predict bowel obstruction during medical treatment of stage IV colorectal cancer.
abstract: BACKGROUND
  In the absence of symptoms related to their primary tumor, patients with stage IV colorectal cancer can undergo medical treatment with their primary tumor in situ. In these patients, bowel obstruction is the most common primary tumor-related complication. We hypothesized that left-sided, circumferential, near-obstructing lesions and/or inability to advance the colonoscope beyond the primary tumor are associated with symptomatic bowel obstruction and are indications for prophylactic primary tumor resection (PTR) or colonic diversion.
  
  
  METHODS
  The medical oncology database of the University of Wisconsin Hospital was retrospectively reviewed. Inclusion criteria were presentation with stage IV colorectal cancer without previous treatment. Student's t-test and Fisher's exact test were used to compare continuous and noncontinuous variables, respectively.
  
  
  RESULTS
  Forty-nine patients met the inclusion criteria. None underwent colonic diversion or stenting during the course of their disease. At presentation, nine patients underwent PTR for obstructive symptoms. Forty percent of patients with high-risk colonoscopic lesions required PTR at presentation, compared with 3% of patients without high-risk findings. No patients with high-risk colonoscopic findings and/or left-sided lesions who did not undergo PTR at presentation developed symptoms of obstruction during medical therapy.
  
  
  CONCLUSIONS
  In stage IV colorectal cancer, circumferential, near-obstructing lesions and inability to advance the colonoscope beyond the primary tumor are common colonoscopic findings and are associated with obstructive symptoms at the time of diagnosis. Left-sided lesions and/or high-risk colonoscopic findings do not predict bowel obstruction during medical treatment and should not be indications for prophylactic PTR or colonic diversion in asymptomatic patients.
authors.affiliation: Department of Surgery, University of Wisconsin, G4/701 Clinical Science Center, 600 Highland Avenue, Madison, Wisconsin 53792-7375, USA.
authors.forename: Nikiforos
authors.initials: N
authors.lastname: Ballian
authors.forename: David M
authors.initials: DM
authors.lastname: Mahvi
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Kennedy
mesh_terms: D000328:Adult; D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000150:complications* / Q000473:pathology / Q000601:surgery; D005260:Female; D006801:Humans; D007415:Intestinal Obstruction / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011446:Prospective Studies