Aspirin and/or Folic Acid in Preventing Recurrent Colorectal Polyps

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)