RecruitingGastrointestinal Biomarkers in Tissue and Biological Fluid Samples From Colorectal Cancer PatientsRATIONALE: Studying samples of tissue, blood, urine, stool, and other biological fluids from patients with cancer and from healthy volunteers undergoing colonoscopy or endoscopy may help doctors identify and learn more about biomarkers related to cancer. PURPOSE: This research study is looking at gastrointestinal biomarkers in tissue and biological fluid samples from patients and participants undergoing colonoscopy, endoscopy, or surgery.