There are three modalities that I’ll mention. One is fecal-occult blood tests, another is flexible sigmoidoscopy, and a third one is colonoscopy. The fecal-occult blood test is meant to detect blood in the stool. The theory is that as the cancer develops, there’s some viability to it – it may shed red blood cells into the lumen of the colon, and if one samples the stool one can find blood.