Study closed to enrollment

Inclusion Criteria:

• Current or prior advanced adenomas
• Advanced adenomas are defined as subject with polyps ≥ 1 cm, tubulovillous adenomas (25-75 percent villous features), villous adenomas (> 75 percent villous), or high-grade dysplasia
• Prior colon cancer (≥ 3 years out from invasive cancer)
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0 or 1
• Ability to under and the willingness to sign a written informed consent document
• Willingness to provide mandatory tissue for research purposes
• Negative pregnancy test ≤ 7 days prior to randomization
• Hemoglobin (Hgb) within normal limits for institution/lab
• Platelet count ≥ 100,000/ul
• White blood cell count (WBC) ≥ 3,000/ul
• Alanine aminotransferase (ALT) ≤ 2 x institutional upper limit of normal (ULN)
• Aspartate aminotransferase (AST) ≤ 2 x institutional ULN
• Total bilirubin ≤ 1.5 x institutional ULN
• Serum calcium ≤ institutional ULN
• Serum creatinine ≤ 1.5 x institutional ULN
• Colonoscopy ≤ 45 days prior to randomization with removal of all adenomas or polyps ≥ 2 mm in size

Exclusion Criteria:

• Any history of current or prior rectal cancer
• Known diagnosis of colon heritable cancer syndrome (familial adenomatous polyposis [FAP], hereditary nonpolyposis colorectal cancer [HNPCC]) or inflammatory bowel disease (Crohn's disease, ulcerative colitis)
• Inability to swallow pills
• Bleeding diathesis
• New diagnosis of carcinoma
• History of hypersensitivity to COX-2 inhibitors, sulfonamides, nonsteroidal antiinflammatory drugs (NSAIDs), salicylates, or ursodeoxycholic acid
• History of gastroduodenal ulcers documented ≤ 1 year
• Known inability to participate in the scheduled follow-up tests
• Significant medical or psychiatric problems which would make the subject a poor protocol candidate, in the opinion of the treating physician
• Total colectomy
• Patients with a colostomy
• History of pelvic or rectal radiation therapy
• History of invasive carcinoma ≤ 5 years (except subjects with Dukes A/B1 carcinoma ≤ 5 years prior to pre-registration or any stage of colon cancer if ≥ 3 years post surgical resection)
• Acute liver disease, unexplained transaminase elevations, or elevated serum calcium
• History of allergic reactions attributed to compounds of similar chemical composition to the study agents
• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia
• Concomitant corticosteroids or anticoagulants needed on a regular or predictable intermittent basis
• New diagnosis of invasive carcinoma
• Use of non-study investigational agent(s) ≤ 3 months prior to randomization
• Chemotherapy ≤ 6 months prior to randomization (Note: topical chemotherapy will be assessed on a case-by-case basis)
• Pregnant women
• Nursing women
• Men or women of childbearing potential who are unwilling to employ adequate contraception
• Regular use of NSAIDs ≤ 6 weeks prior to randomization, defined as a frequency of 7 consecutive days (1 week) for > 3 weeks (Exception: low dose aspirin [81 mg] for those subjects who are chronic users of aspirin prior to the beginning of the study)