This hypothetical consultation about screening for colon cancer is presented for purposes of general information. If you think you are at high risk for this condition or have any questions about colonoscopy, please see your doctor to discuss your individual case and the exams and treatments that are best for you.
Colon cancer, which includes cancer of the colon and cancer of the rectum, is the fourth most common cancer in both men and women in the United States. Over 90 percent of cases of colon cancer occur in individuals who are over 50 years of age, and the average colon cancer patient is in his or her mid-sixties when the cancer is discovered. In our example, the patient is a 50-year-old man who is about to undergo a routine screening exam.
Doctor: Hello. How are you?
Patient: Fine, thank you, and you?
Doctor: I’m doing well.
Patient: My doctor has sent me because I’m 50 years old and he says I have to be screened for colon cancer. I have to tell you I have little enthusiasm for this, but I’m here.
Doctor: All right. Do you understand what is involved with a colonoscopy?
Patient: I do not.
Doctor: We screen patients beginning at age 50 who are at average risk for colon cancer, meaning they have no family history or personal history of cancer or polyps to help prevent the development of colon cancer. Colon cancer is one of the few preventable cancers. It’s the second leading cancer in both men and women and the fourth leading cancer in the United States.
Patient: I don’t have any problems. Why all of a sudden do I hit 50 and now I need to do this?
Doctor: We believe that one of the risk factors for colon cancer is age, and that age has been determined to be roughly around the age of 60. We also know that polyps, which are kind of a growth that develops in the colon, begin approximately 10 years before a cancer develops. There is a very well-defined sequence of a polyp -- over the course of time it will undergo several changes that can turn it into a colon cancer. If we remove those polyps early, we eliminate the risk of colon cancer. That’s why, because the risk factor begins at around age 60, we try to screen people beginning at age 50, ten years before the cancer will develop, to remove polyps. We know that about 25 percent of patients who are screened for colonoscopy around the age of 50 will have a polyp.
Patient: What exactly is involved in this?
Doctor: The day before the procedure, we have you do what’s called a bowel prep. A bowel prep is a liquid that you will drink that will give you diarrhea but will clean the colon so that we can get a good examination of it. We’ll ask you to be on clear liquids the day before and keep yourself well hydrated. Then the day of the procedure, you’ll come in, you’ll get checked in to same-day procedures, we’ll start an IV on you to hydrate you, and we’ll bring you back to the endoscopy suite. In the endoscopy suite, you’ll have a nurse and myself present. The nurse will hook you up to monitors so we can monitor your heart rate and blood pressure and your breathing, and then we’ll administer sedation so that we can keep you comfortable during the procedure. We then begin the colonoscopy when we think that you’re adequately sedated. The examination begins with introduction of the colonoscope into the anus and we slowly advance it under direct visualization through the entire colon. All the while we’re examining the colon and looking for polyps and other abnormalities. Once we reach the end of the colon, we then remove the scope slowly and take a second look to look for any other abnormalities, and then the procedure is over. The recovery time is usually 30-40 minutes, where the sedation wears off and you’re given some clear liquids to drink. And as soon as you’re feeling okay, you can go home. You’ll need to find someone to drive you home because of the sedation we give you, and for the rest of the day, take it easy. But most patients do fine by the afternoon of the exam and almost everybody returns to work the next day
Patient: Are there complications to this procedure?
Doctor: The complications of the procedure have to do with the possibility of perforation. In less than 1 percent of cases, the colonoscope can sometimes cause an injury to the bowel, where a hole is made in the bowel. Many times we can manage that with just IV antibiotics and observation, but it does mean a hospitalization. But it can also mean that a surgeon needs to take you to the operating room to repair the hole, which may mean a more prolonged hospitalization. Other risks have to do with the sedation, when your blood pressure or your heart rate may change such that we have to stop the procedure. And finally there’s a risk of bleeding when we do remove the polyps, we sometimes can have a little bit of bleeding. That, again, usually stops on its own, but sometimes we require a second colonoscopy to stop the bleeding.
Patient: Does that mean I need to stop my aspirin before I have this surgery?
Doctor: We ask that you stop aspirin and Motrin one week before the procedure and any other blood thinners that you may be on, and that you don’t resume those until five days after the procedure.
Patient: Following the procedure, you said I can go back to work the next day?
Patient: When can I start exercise?
Doctor: The next day.
Patient: Are there any things that make it more likely that you’ll find abnormalities?
Doctor: When patients have a significant family history, that increases the risk that we may find polyps. What’s considered a significant family history is when you have a first-degree relative who has had colon cancer or rectal cancer, or a first-degree relative under the age 60 who is known to have polyps. Other risk factors include polyp syndromes, which are genetic abnormalities, and
inflammatory bowel disease such as Crohn’s disease and ulcerative colitis.
Patient: So the fact that my father had polyps and had several removed is not good.
Doctor: Depending on the age at which he had the polyps. If he had the polyps after age 50 or 60, that might be still considered an average risk for you. If he had the polyps before age 60, then we would say that you are slightly higher risk than the average person.
Patient: Why can’t you just screen like looking for blood?
Doctor: In the past, we had screened using what’s called fecal occult blood testing (FOBT), although we found that there were a lot of false positive, and so we were sending patients unnecessarily for screening colonoscopies. And we also found that in patients who had cancers that fecal occult blood was not picking them up by finding blood in the stool. So it’s not a very effective tool. The FOBT is all we have in certain parts of the world but the current recommendations from the colorectal societies and from the American Gastroenterological Society and the American Cancer Society is that people get their screening colonoscopies at age 50. The procedure is paid for by almost all insurance companies including Medicare.
Patient: Why do we polyps form? Is it something related to diet, or is it just age and bad luck?
Doctor: In addition to the risk factors that I mentioned, age is a risk factor, so bad luck does play a role in it. A Western diet or high fat diet has been identified as a risk factor. The role of fiber in the diet has raised some debate recently, but we still believe that a high-fiber diet is good, not only for good intestinal health, but also has many other benefits such as cardiovascular health as well.
Patient: You read in the newspapers about something called “virtual colonoscopy.” Is that an alternative, and should I be thinking about that?
Doctor: Virtual colonoscopy is an exciting area for potentially screening patients for polyps and colon cancer. It, however, is still in the investigational stage and has not been recommended as a mechanism for screening at this point. But a virtual colonoscopy is essentially a CT scan of the abdomen and pelvis where a patient goes to radiology, a small amount of air is injected into the patient’s rectum, and then a scan is performed of the abdomen. The scan itself can take anywhere from several seconds to a minute. And then an image is generated of the colon that the radiologist evaluates for the presence of polyps or other lesions. The problem with virtual colonoscopy at this point is that it is not very good at detecting small polyps and therefore is not being recommended as a good screening tool. In the future, it will play a greater role as our technology improves. I think the one area where virtual colonoscopy will make a big impact is when patients don’t have to do a bowel prep. So unfortunately at this point, patients are still having to do the bowel prep the day before the procedure, but some time in the future, we expect that that will not be necessary and that will greatly improve our ability to increase the number of patients who are willing to get screened as well as our detection of polyps.
Patient: Well, it sounds like it is my time for a colonoscopy. How do I sign up for them?
Doctor: My office will set that up for you and contact you very shortly.
Read more at
Colorectal Surgery and
Moores Cancer Center at UC San Diego Health. Also see the health library entry for