DISEASE CHARACTERISTICS:

• At risk for colorectal cancer

  • History of histologically proven sporadic colon adenomas or colon cancer
  • At least 5 aberrant cryptic foci on sigmoidoscopy
  • Less than 20 prior cumulative adenomas and no heredity nonpolyposis colorectal cancer

• No significant asymptomatic lesions on sigmoidoscopy, including any of the following:

  • Inflammation
  • Strictures
  • Anorectal lesions
  • Fistulae
  • Vascular lesions
• No adenomas or colon carcinomas on flexible sigmoidoscopy
• No history of gastrointestinal (GI) cancer other than colorectal cancer
• No inherited colorectal cancer syndromes

PATIENT CHARACTERISTICS:

• No other GI mucosal epithelial diseases (e.g., Barrett's esophagus, chronic or recurrent peptic ulcer disease, celiac sprue, or other disorders of nutrient absorption)

  • No active peptic ulcer disease
• No history of inflammatory bowel disease (ulcerative colitis or Crohn's disease)
• No known or suspected alcohol ( > 5 glasses of wine or beer per day), drug, or medication abuse
• No quantitative or qualitative platelet or coagulation abnormalities
• No personal or family history of a bleeding disorder
• No uncontrolled diabetes
• No uncontrolled hypertension, or chronic congestive heart failure (New York Heart Association class II-IV heart disease)
• No myocardial infarction, transient ischemic attack, or stroke within the past 6 months
• No equilibrium disorders affecting gait or ability to stand that would preclude study participation
• No involuntary change in weight (up or down) of ≥ 15% of usual body weight within the past year
• Creatinine ≤ 2.0 mg/dL
• No chronic liver disease or pancreatitis
• No allergies to aspirin
• No prior severe adverse reactions to NSAIDs such as asthma, GI bleeding, or renal insufficiency
• No institutionalized, mentally disabled patients
• No prisoners
• Not pregnant or nursing
• Fertile patients must use effective contraception
• Negative pregnancy test

PRIOR CONCURRENT THERAPY:

• No concurrent antibiotic prophylaxis
• More than 7 days since prior nonsteroidal anti-inflammatory drug (NSAID) treatment, including aspirin
• No concurrent frequent use (> 7 days in previous month) of NSAIDs, cyclooxygenase (COX)-2 inhibitors, nitrovasodilators, or oral corticosteroids
• No concurrent macronutrient consumption below the 1st or above the 99th percentile of U.S. consumption
• No concurrent anticoagulants, ticlopidine, and clopidogrel
• More than 3 months since prior general anesthesia
• More than 3 months since prior investigational agents

• No concurrent NSAIDs, including aspirin or COX-2 inhibitors

  • Acetaminophen allowed
• No concurrent nitrovasodilating drugs
• More than 3 months since prior participation in other investigational trials