A Trial of Omeprazole and Low Dose Aspirin to Identify Colorectal Biomarkers of Preventive Efficacy

This trial will obtain biomarker data on the possible preventive effects of omeprazole and low-dose aspirin in colorectal tissue. Persons who have had 5 or more adenomas, 5 or more serrated polyps, or an incompletely removed adenoma or serrated polyp in the colon or rectum are potentially eligible. Before participating in the study, study staff will explain the study and review the consent form. If you are interested and provide consent, study staff will then confirm your eligibility. Once enrolled, participants will take two 20 mg omeprazole tablets and two 81 mg aspirin tablets each day before the first meal each day for 25-45 days. The study does involve biopsies of the colorectal tissue before and after taking the study medications. The biopsies are samples of tissue, about the size of a grain of rice, that will be taken from the colon or rectum before and after taking the study medications. This is done during a usual, clinical colonoscopy exam and during one more limited exam, called flexible sigmoidoscopy, that is done for the research study. The flexible sigmoidoscopy requires less preparation. Which procedure comes first depends on what fits best with each participant's clinical scenario. Biopsies of both normal mucosa and polyps (if possible) are collected.