Measurement of NK Cell Activity in Whole Blood in Subjects Being Screened for Colorectal Cancer Using Colonoscopy

Inclusion Criteria: * Subjects undergoing colonoscopy at the hospital * Subjects who have adequately prepared for their colonoscopies as per their doctor's directions * Subjects whose colonoscopy preparation has been deemed to be excellent or sufficient during the colonoscopy procedure * Subjects who provide informed consent to participate in the trial * Subjects \>40 years of age Exclusion Criteria: * Lack of understanding and/or participation due to illiteracy * History of Active viral or bacterial infection * History of prescription use of immunosuppressive drugs within the last six months * History of anticancer treatments including surgery or chemotherapy * History of autoimmune disorders (rheumatoid arthritis, multiple sclerosis, systemic lupus erythematosus, inflammatory bowel disease including Crohn's disease, Type I diabetes, Guillain-Barré syndrome) * Known HIV, Hepatitis B, or Hepatitis C infection * Currently participating (or participated within the previous 120 days) in an investigational therapeutic or device study * Female who is pregnant, nursing, or of child-bearing potential while not practicing effective contraceptive methods.