For colon cancer screening, the finger examination of your rectum does not offer very much information because of the short distance that is examined. It is limited to the first 3 or 4 inches inside your rectum. However, the finger exam is very important for the diagnosis of prostate cancer in men. During the finger exam, the stool can be tested for blood. This is a simple colon cancer screening procedure, but it is not nearly as accurate as colonoscopy.