FAP in the Small Intestine

Steven Gallinger, MD, Department of Surgery

Years ago, it was believed that FAP only affected the large bowel because of the large number of adenomas, or precancerous polyps, in that area. Over the last fifteen years, it has become clear that smaller numbers of polyps may form in the small intestine, mostly without any warning symptoms. The polyps appear to cluster in an area of the small intestine just beyond the stomach where bile and pancreatic juice enters the bowel. Polyps may also develop in the first part of the small intestine called the duodenum.

Not everyone with FAP will develop polyps outside the large bowel. It appears that as patients get older, there is a higher risk for polyps in the small intestine. Just because a father with FAP may have duodenal polyps does not mean his son or daughter will be similarly affected. However, some families do have more than one family member with duodenal polyps which can place a patient at higher risk for larger polyps. Generally, polyps in the small intestine tend to grow more slowly and less abundantly than polyps in the large bowel. Many patients worry that they will need surgery in an area where they digest their food. The best way to prevent a problem may be staying a step ahead and having regular check-ups so that surgery is not needed. It is reassuring to know that patients can be treated in other ways today.

Some patients may develop a different kind of polyp in the stomach, usually in the upper stomach. Stomach polyps tend to be tiny in size but large in number. This may alarm patients until they learn that these polyps are generally not precancerous and merely require confirmation by checking the tissue.

Every patient with FAP should have both areas examined to find out whether any polyps have developed. It is a good idea to have this test at the time the large bowel is removed or shortly thereafter. However, for those who had their bowel surgery years ago, it is never too late to discuss this test with your physician. Patients who have the test always get local freezing for the back of their throat and sedation is given as well. Once this happens, a special fibre optic tube called a SIDE-VIEWING ENDOSCOPE is inserted through the patient's mouth so that the physician is able to clearly see the stomach and upper intestine. The benefit of endoscopy is that all or part of any polyp seen can be removed through the tube and BIOPSIED, that is, analysed under the microscope. Based on the findings at this first examination, the patient will join one of four groups:

1. No polyps in the stomach or small intestine
2. Small (less than 1-2 mm) polyps
3. Medium (2-10 mm) polyps
4. Large (greater than 10 mm) polyps

Most patients have 1-2 mm polyps in or around the opening of the duodenum. The occasional patient will have large polyps which are of more concern. In the case of patients in Category 4, the polyps should be removed because they have a higher likelihood of changing to cancer. A specialists in this area may be able to remove large polyps using LASER, or electric current, at the time of the endoscopy. Patients can be referred to an appropriate specialists through the Famlial GI Cancer Registry or their own physician.

Future check-ups will depend on the size or absence of any polyps. It is important not to overtreat patients but rather to balance the timing of examinations according to the type of polyps seen in the small intestine. For example:

The purpose of these check-ups is to detect polyps which have the potential to become cancerous. With this goal in mind, we are looking for genetic changes in polyps to predict which patients should be followed more closely.

Research can help patients in two ways. First, by identifying patients at high risk, efforts can be directed toward preventing duodenal cancer in a small group of patients. Second, other forms of treatment are being discovered. New drugs are being tried which can either prevent polyps from increasing in number or from growing back once they have been removed in the small intestine. The more you learn about prevention, the better you will be able to improve your own health care.