Inclusion Criteria

DISEASE CHARACTERISTICS:

- At least 1 prior resected colorectal adenoma within the past 5 years

- At least 3 mm in size

- No personal or family history of familial adenomatous polyposis

PATIENT CHARACTERISTICS:

Age:

- 40 to 80

Performance status:

- SWOG 0-1

Life expectancy:

- Not specified

Hematopoietic:

- Hematocrit at least 35%

- WBC at least 4,000/mm^3

- Platelet count at least 100,000/mm^3

Hepatic:

- Bilirubin no greater than 2.0 mg/dL

- AST and ALT no greater than 2 times normal

Renal:

- Creatinine no greater than 1.5 mg/dL

- No greater than 1+ protein, 0-3 casts, and 0-5 WBCs and RBCs in urine

Gastrointestinal:

- No requirement for special diet or additives

- No diet that would preclude taking study medications

- No gastric or duodenal ulcer within the past year

- No inflammatory bowel disease

Other:

- No more than 20 dB hearing loss for age at any frequency

- No prior or concurrent invasive cancer within the past 5 years except nonmelanomatous
skin cancer, melanoma in situ, stage I cervical cancer, stage I colon cancer, or
stage 0 chronic lymphocytic leukemia

- No severe metabolic disorder or other acute or chronic diseases

- No history of or predisposition to abnormal wound healing or repair

- No allergies to nonsteroidal anti-inflammatories or eflornithine

- Not pregnant or nursing

- Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- Not specified

Chemotherapy:

- No concurrent chemotherapy

Endocrine therapy:

- No concurrent corticosteroids

Radiotherapy:

- No concurrent radiotherapy

Surgery:

- See Disease Characteristics

Other:

- No other concurrent nonsteroidal anti-inflammatories or anticoagulants administered
on a regular or predictable intermittent basis

- No concurrent aspirin greater than 81 mg per day or 325 mg twice a week for
cardiovascular disease prophylaxis

- No concurrent calcium supplements greater than 500 mg/day