What is Familial Adenomatous Polyposis ?

Familial Adenomatous Polyposis is a hereditary disease, which is to say that it is due to the mutation of a gene, and this modification can be passed on from one generation to the next. It is not a contagious disease. It is characterized by the growth of a large number (hundreds and even thousands) of polyps on the colon and rectum. These polyps, called adenomas, grow on the mucosa of the colon and the rectum. In the absence of proper surgical treatment, the growth and transformation of one or more of these adenomas into cancer is unavoidable.

The polyps generally appear in patients as young as 10 – 12 years old, but the transformation into cancer rarely occurs before age 20. However, in the absence of treatment, these polyps degenerate into cancer in most patients by age 40. Therefore, treatment should ideally take place by age 20.

How is Familial Adenomatous Polyposis passed on ?

If a person with FAP wishes to have a family, the risk of passing on the disease to each of their children is 50 %. This percentage of risk is an average, which can in some families reach a much higher proportion of children afflicted by the disease. Those children who do show the genetic mutation, will develop these polyps and will be at risk of passing the gene on to on average, 50 % of their children. The children who do not have the genetic mutation will not develop the disease and do not have any risk of passing it on to their children.

In some rare cases, some people may be a polyposis gene carrier, even though neither of their parents has the disease. These people have a genetic mutation that occurred before birth, and can pass it on to their children. This passing on of the genetic alteration is identical to that of those patients having true familial polyposis.

Clinical Symptoms

When these polyps first develop, there will be no outwardly visible symptoms. At most, they may cause a few abdominal pains or intestinal transit problems. Signs of blood in the stool may be a warning sign, but rarely occur. The presence of symptoms generally begins much later, by which time the polyps may already have begun to become cancerous. This is why it is very important to have a diagnosis before there are any symptoms. This obviously shows the crucial nature of a thorough family history and genetic research on the whole family, so that diagnosis in one patient can lead to the identification of every family member who may be carrying the disease.

Apart from the intestinal polyps, FAP may also present other systemic manifestations, whose presence may lead to a diagnosis. These lesions or cysts, called epidermoid cysts, are varied and develop differently in different patients. For example, they may be :

♦ cysts just under the skin, called epidermoid cysts, which never become cancerous

♦ bone tumors or osteomas, also non-cancerous, which may be located in the jaw, the skull, or occasionally in other bones

♦ polyps in the stomach and the duodenum. These duodenal polyps may become cancerous, and therefore require regular endoscopic monitoring by a gastro-enterologist

♦ benign lesions of the retina, which appear as tiny black marks called congenital hypertrophy of the pigmented retinal epithelium (ie thickening dermoid conjunctival tissues). These lesions will only rarely affect the vision of the patient.

♦ Dermoid tumors, excessive development of conjunctival tissues, which appear as a hard and fibrous thickening, rather like scar tissue. These are benign tumors, but may with growth push or compress organs around them. The develop inside the abdomen or on the abdominal muscles.

Early detection and treatment of these growths can range anywhere from simple medical screening, to treatment with drugs, and more rarely to surgical intervention, to be decided by medical specialists. 

How is FAP detected in a family at risk ?

The most basic way is to take a full family history in order to draw up a genetic family tree. Then family members can get genetic counselling. Genetic testing and analysis of blood samples from various family members can be done by a doctor specialized in molecular genetics, to determine if the patient at risk has inherited the gene associated with the disease. This testing can provide information to the family doctor as to the granting of medical benefits and subsidies to the people carrying the genetic mutation.

Apart from clinical examinations, two other types of testing can be done :

♦ Examination of the retina by an ophthalmologist may allow detection of congenital hypertrophy of the pigmented retinal epithelium. This is visible by examination of the fundus (back of the eye) in an office consultation, by means of a three-mirrored ophthalmoscope. In about 70 % of families, this symptom is present in all the family members carrying the disease, and should be screened for in all the children whose parents have the disease. It can be present already in childhood. In other families, this symptom is absent.

♦ Examination of the colon and rectum by a gastro-enterologist. Depending on the case, the screening can be done by recto-sigmoidoscopy or by colonoscopy. This test allows the doctor to detect polyps in the intestines. In the absence of any symptoms, this kind of screening should be done yearly, starting at age 11. Polyps might not show up the first year, but could well show up later.

If polyps are detected by recto-sigmoidoscopy, there should be a follow-up exam by total colonoscopy (study of the entire colon) which can determine the extent of the polyposis. The presence of polyps means surgical treatment should take place before the age of 20.

Treatment of Familial Adenomatous Polyposis

These polyps may not be removed one by one because there are so many of them, and they grow back too quickly. That is why surgical intervention is the only effective treatment. Several techniques are used with some success, and are chosen to suit the particular case. Even if these operations may seem radical, they are the only way to prevent cancer of the colon, which would be unavoidable without surgery. These are the most common types of operations :

♦ Total colectomy with ileo-rectal anastomosis. This operation involves removal of the whole colon. The end of the small intestine is then joined to the rectum. After surgery, intestinal transit will be from 2 to 4 stools per 24 hour period. This operation spares the rectum, which must then however be monitored twice a year by proctoscopy, during which any polyps present are removed. This monitoring must continue throughout the lifetime of the patient. If the number of polyps on the rectum were to become excessive, it would then be possible to surgically remove the rectum and transform the ileo-rectal anastomosis into an ileo-anal anastomosis, described hereafter.

♦ Colo-rectal excision with ileal reservoir and ileo-anal anastomosis. This operation consists in excision of the entire colon and the rectum, thus removing all the mucosa where the polyps grow. The anus and sphincter remain as they are. The end of the small intestine is folded over on itself to form a pocket (ileal reservoir) whose function is to replace the rectum. This pocket is brought down to the anus where it is joined. Sometimes this splice has to be temporarily protected from the passage of fecal matter by joining the next to last section of the small intestine to the skin of the abdominal wall. This joining of the small intestine to the skin, called a temporary ileostomy, is then removed 8 to 10 weeks later, by means of a second, simpler operation. After this operation, bowel movements occur 4 to 5 times per 24 hour period.

♦ Colo-rectal excision with ileostomy. This operation is much more rarely performed, and is reserved for patients having already developed cancer of the rectum, or who must not have ileo-anal anatomosis for another reason. The end of the small intestine is permanently joined to the skin of the abdominal wall, and patients have a bag where fecal matter is deposited.

How long does the operation last and how long is recovery ?

The hospital stay will vary depending on which type of surgery is performed, but generally it will be 10 to 15 days. In the case of an ileo-anal anastomosis, the removal of the protective ileostomy requires a second hospital stay of 7 to 8 days. Recovery at home will take 4 to 6 weeks, and the beginning of this convalescence necessitates a certain limitation of activities. The patient may go back to work 6 to 8 weeks after leaving hospital. Before leaving the hospital, the patient will see the doctor and a dietician to establish the proper diet restrictions to follow. During the first few weeks of recovery, doctors recommend a diet that is low in fiber, avoiding fruits and vegetables. The patient can then progressively re-introduce foods into their diet, depending on how the body reacts.

Life after surgery

Just a few months after surgery, most patients are able to eat without particular restrictions, and lead a pretty normal life. A few patients may have accelerated bowel movements. This can be controlled with drugs that slow down intestinal transit. Otherwise their lives will be normal. Sexual activity will not be affected by the surgery if it is done at an early stage in the disease. As long as there is no rectal cancer, none of the operations have any effect on fertility or on subsequent pregnancies.