Gastrointestinal Biomarkers in Tissue and Biological Fluid Samples From Colorectal Cancer Patients

This study is collecting tissue and fluid samples from patients undergoing colonoscopy or endoscopy to study biological markers of digestive tract cancers, polyps, and inflammatory bowel disease. **You may be eligible if...** - You are having a colonoscopy or endoscopy at Vanderbilt University Medical Center or the Veterans Affairs Medical Center - You have a diagnosis of gastrointestinal (GI) cancer, polyps, or inflammatory bowel disease, OR you have a history of previously treated GI cancer, polyps, or inflammatory bowel disease - You are able to give informed consent - You are not mentally or medically impaired **You may NOT be eligible if...** - You have a bleeding disorder Talk to your doctor to see if this trial is right for you.