OBJECTIVES:~Primary~Compare the effects of celecoxib vs placebo on the number of rectal aberrant crypt foci in patients with premalignant rectal polyps or prior sporadic colorectal neoplasia.~Secondary~Compare the effects of these drugs on proliferation index, apoptotic index, and gene expression patterns in ascending and descending colon tissue from these patients before and after treatment.~Assess gene expression patterns in normal mucosa from the ascending vs descending colon in patients referred for screening, surveillance, or diagnostic colonoscopy.~OUTLINE: This is a randomized, double-blind, placebo-controlled, chemoprevention study. Patients are stratified according to age (18 to 49 vs 50 and over) and number of rectal aberrant crypt foci (5-9 vs 10 or more).~All patients undergo a baseline biomarker assessment and full colonoscopy to resect all neoplasms, quantitate rectal aberrant crypt foci, and biopsy rectal mucosa.~Depending on the results of the biomarker assessments, patients are randomized to 1 of 2 treatment arms. Patients with no adenomas of 5 mm or greater receive no further treatment.~Arm I: Patients receive oral celecoxib twice daily.~Arm II: Patients receive oral placebo twice daily. In both arms, treatment continues for 6 months in the absence of unacceptable toxicity.~All patients undergo an endoscopic exam of the colorectum at completion of study.~PROJECTED ACCRUAL: A total of 100 patients will be accrued for the baseline biomarker assessment and a total of 40 patients (20 per arm) will be accrued for the chemoprevention study within 1 year.
RATIONALE: Celecoxib may be effective in preventing colorectal cancer in patients who have a history of rectal polyps or colorectal neoplasia.~PURPOSE: Randomized phase II trial to study the effectiveness of celecoxib in preventing colorectal cancer in patients who have a history of rectal polyps or colorectal neoplasia.