I have several symptoms of colon cancer (though it could be something else), including changed bowel habits, occasional bright red blood in the stool and narrower than normal stool. I've had a blood sample analysed and apparently the results were normal (though I don't know what they tested for), and I'm about to have an examinaton that the doctor in general surgery told me would look at the first 20cm of the rectum/colon and would detect 75% of what he called "the nasties" (I guess that means polyps, tumours or other problems).
My question is: are the blood test and that physical examination enough to rule out colon/colorectal cancer? Or should I ask for another test, such as analysis of a stool sample?