This is a randomized controlled trial of aspirin and/or folate supplementation for the prevention of the recurrence of neoplastic polyps (adenomas) of the large bowel.

This is a randomized controlled trial of aspirin and/or folate supplementation for the prevention of the recurrence of neoplastic polyps (adenomas) of the large bowel among subjects with a recent history of these tumors. The study is a randomized, double-blind, placebo-controlled trial with a 2 x 3 factorial design.

Inclusion Criteria:

1. One neoplastic polyp removed within three months of study entry or within 16 months of study entry if over 1 cm in size or if subject has had a lifetime history of at least two polyps, with the entire large bowel seen by colonoscopy to be free of further polyps within 3 months of entry.
2. An ability and willingness to follow the study protocol, as indicated by the subject's giving informed consent to participate.
3. Good general health, with no severely debilitating diseases or active malignancy that might compromise the patient's ability to complete the study.
4. Anticipated colonoscopic follow-up three years after the qualifying colonoscopy.
5. Age between 21 and 80 years at the time of the intake colonoscopy.
6. For women of childbearing potential, agreement to use effective birth control for the duration of the study.
7. Intent not to take aspirin or aspirin-containing products, NSAIDs or folic acid for the length of the study unless required by a physician.
8. Not randomized previously or currently in a chemoprevention trial, except for the: "Nutritional Prevention of Large Bowel Polyps" Study (Polyps Prevention Study I); and brief participation in the "VA Cooperative Study" with no continuing involvement.

Exclusion Criteria:

1. Invasive carcinoma in any colonic polyp removed.

2. Familial colonic polyposis syndromes.

3. Ulcerative colitis or Crohn's disease.

4. Malabsorption syndrome (e.g. pancreatic insufficiency).

5. Large bowel resection for any reason.

6. Diagnosed narcotic or alcohol dependence

7. Contraindication to aspirin use, including:

   1. documented peptic ulcer disease in the past 20 years
   2. aspirin sensitivity
   3. bleeding diathesis, including hemorrhagic stroke

8. Likelihood of NSAID use

   1. recurring arthritis or other musculo-skeletal problems
   2. frequent NSAID use in 5 years preceding
   3. history of stroke or TIAs
   4. history of angina or myocardial infarction
   5. desire to take aspirin for the prevention of cardiovascular disease

9. Required or contraindicated folic acid use pernicious anemia or folic acid deficiency

10. Pregnancy or lactation.