RATIONALE: Chemoprevention therapy is the use of certain drugs to try to prevent the development or recurrence of cancer. The use of aspirin and/or folic acid may be effective in preventing recurrent polyps in patients who have had polyps removed previously.

PURPOSE: Randomized clinical trial to determine the effectiveness of aspirin and/or folic acid in preventing the recurrence of colorectal polyps.

OBJECTIVES:

• Determine whether aspirin and/or folic acid prevents recurrence of colorectal adenomas in patients who have had colorectal adenomas removed.

OUTLINE: This is a randomized, double-blind, placebo-controlled, multicenter study. Patients are randomized to 1 of 4 treatment arms.

• Arm I: Patients receive oral aspirin and oral folic acid daily.
• Arm II: Patients receive oral aspirin and oral placebo daily.
• Arm III: Patients receive oral placebo and oral folic acid daily.
• Arm IV: Patients receive 2 oral placebos daily. In all arms, treatment continues for 3 years in the absence of unacceptable toxicity.

After completion of the 3-year intervention, all patients undergo a surveillance colonoscopy.

Peer Reviewed and Funded or Endorsed by Cancer Research UK

PROJECTED ACCRUAL: A total of 1,300 patients will be accrued for this study.

• Dietary Supplement: folic acid
• Drug: acetylsalicylic acid

DISEASE CHARACTERISTICS:

• Histologically confirmed colorectal adenoma removed within the past 6 months

  • Greater than 0.5 cm after fixation or greater than 0.7 cm at time of removal

    • OR
  • Any size with a history of prior colorectal adenoma removal(s)
• Removed via colonoscopy, flexi-sigmoidoscopy (provided barium enema has been performed), or transanal endoscopic microsurgery
• Removal must be considered complete with follow-up to be done within 6 months
• No prior resection of large bowel (e.g., hemi-colectomy or greater, anterior resection, or subtotal colectomy)

PATIENT CHARACTERISTICS:

Age:

• 75 and under

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• No active bleeding disorders

Hepatic:

• Not specified

Renal:

• Not specified

Cardiovascular:

• No unstable heart conditions

Pulmonary:

• No unstable asthma

Other:

• Not pregnant and no potential to become pregnant within the next 3 years
• No unstable diabetes
• No active upper gastrointestinal ulceration
• No known aspirin intolerance or sensitivity
• No other serious medical conditions that would preclude study participation

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• Not specified

Endocrine therapy:

• Not specified

Radiotherapy:

• Not specified

Surgery:

• See Disease Characteristics

Other:

• No other concurrent folic acid
• No concurrent anticoagulants
• No other prior or concurrent non-steroidal anti-inflammatory drugs, prescribed or self-medicated (more than 3 tablets per week)