A 47-year-old male comes to your office for his annual check-up. He states that he passed some blood two weeks ago, on one occasion, when he defecated. He has no other symptoms and he describes his health as excellent. He watches his diet and exercises regularly. He is a non-smoker, drinks alcohol socially, 1-2 times per week, and has no family history of GI disease. Your physical examination is normal. Rectal exam is negative, no stool present in the vault.