DISEASE CHARACTERISTICS:

• History of colonic neoplasia, defined as 1 of the following:

  • Colonic adenoma > 5 mm within the past 5 years
  • Known adenoma on present exam
  • Colon cancer within the past 5 years
• No evidence of active malignant disease

• Scheduled to undergo colonoscopy

  • Must have at least 5 aberrant crypt foci (ACF) on baseline colonoscopy

PATIENT CHARACTERISTICS:

• ECOG performance status (PS) 0-1 (Karnofsky PS 70-100%)
• Leukocyte count ≥ 3,000/μL
• ANC ≥ 1,500/μL
• Platelet count ≥ 100,000/μL
• INR ≤ 1.5
• Total bilirubin ≤ 1.5 times upper limit of normal (ULN)
• AST and ALT ≤ 1.5 times ULN
• Estimated glomerular filtration rate > 45 mL/min
• BUN < 40 mg/dL
• Not pregnant
• Negative pregnancy test
• Fertile patients must use effective contraception

• No uncontrolled intercurrent illness including, but not limited to, any of the following:

  • Ongoing or active infection
  • Symptomatic congestive heart failure
  • Unstable angina pectoris
  • Cardiac arrhythmia
• No psychiatric illness or social situations that would limit compliance with study requirements
• No history of adverse reactions attributed to compounds of similar chemical or biologic composition to PEG, bisacodyl, or methylene blue
• No inflammatory bowel disease
• Willing to forego PEG laxative during the study period
• No known or suspected bowel obstruction
• No average of > 2 bowel movements per day or watery or loose stools within the past 90 days as assessed by self-report at baseline
• No evidence of proctitis (e.g., due to radiation, inflammatory bowel disease, infection) by history or endoscopy
• No history of baseline diarrhea

PRIOR CONCURRENT THERAPY:

• No prior removal of the rectum
• No radiation to the rectum within the past 24 months
• No systemic chemotherapy for any cancer within the past 18 months
• No other investigational agent within the past 30 days
• More than 3 months since prior and no concurrent suppository medication or enema, except as directed for colonoscopy or flexible sigmoidoscopy procedure bowel preparation
• More than 3 months since prior polyethylene glycol (PEG), except as part of colonoscopy preparation
• No concurrent systemic corticosteroids
• No concurrent anticoagulant therapy
• Concurrent cardioprotective aspirin dose allowed provided the patient has been on a stable dose for the past 3 months AND agrees to remain at that dose during the study period
• Concurrent therapeutic (e.g., pain relief) NSAIDs allowed provided their use is limited to ≤ 30 cumulative days during the study period

• Concurrent non-PEG laxatives allowed provided the dose has been stable for the past 90 days

  • Must agree to restrict any additional laxative use to the rescue medication (i.e., bisacodyl) provided
  • No concurrent PEG-containing laxatives