LAUSR

524Background: The APC trial showed that patients at high risk for colorectal adenoma development experienced a 33-45% reduction in post-polypectomy adenoma detection when treated with the selective cyclooxygenase-2 (cox-2) inhibitor, celecoxib. Unfortunately, this study also found a small increased risk of cardiovascular toxicity among celecoxib users, preventing broad use of this agent for chemoprevention. Celecoxib inhibits expression of prostaglandin E2 (PGE2), an inflammatory mediator produced by fatty acid metabolism via cyclooxygenases, and degraded through the activity of 15-prostaglandin dehydrogenase (15-PGDH). Methods: Adenomas collected from APC trial participants prior to treatment were examined using immunohistochemistry (IHC) to assess expression of cox-2 (high vs. low) and 15-PGDH (present vs. absent). A combined variable to estimate tumor PGE2 levels identified cases as PGE2 low (Cox-2 low/15-PGDH present) or PGE2 high (Cox-2 high/15-PGDH present; Cox-2 high/15-PGDH absent; or Cox-2 low/1...