Colonoscopy or Fecal Occult Blood Test in Screening Healthy Participants for Colorectal Cancer

OBJECTIVES: * Compare the neoplastic outcome of participants at average risk for colorectal cancer who undergo colonoscopy vs annual fecal occult blood tests. * Compare the endoscopic and clinical resources required for these screening methods in these participants. * Compare the benefit-to-harm ratio in participants undergoing these screening methods. * Determine the level of participation of participants undergoing these screening methods. OUTLINE: This is a randomized, two-part, multicenter study. Participants are asked whether they are interested in participating in a randomized controlled trial of colorectal cancer screening. * Screening colonoscopy feasibility study I (accrual completed as of 12/14/2004): Participants who are interested in participating in a screening trial are randomized to 1 of 2 screening arms. * Arm I: Participants undergo baseline screening colonoscopy. * Arm II: Participants receive standard care. * Screening colonoscopy feasibility study II: Participants who are interested in participating in a screening trial are randomized to 1 of 2 screening arms. * Arm I: Participants undergo baseline screening colonoscopy. Participants are given individualized recommendations for further surveillance based on the results of the colonoscopy. * Arm II: Participants undergo a baseline fecal occult blood test (FOBT). Participants are given individualized recommendations for further surveillance based on the results of the FOBT. Participants with negative baseline FOBT undergo FOBT annually for up to 4 years in the absence of a positive FOBT. All participants are followed annually for up to 4 years. PROJECTED ACCRUAL: A total of 1,402 participants (701 per screening arm) have been accrued for feasibility study I within 3 years (accrual completed as of 12/14/2004). An additional 3,550 participants (1,775 per screening arm) will be accrued for feasibility study II within 5 years.