What is Colonic polyps and hereditary polyposis syndromes

Colonic polyps is a disease of the gastrointestinal tract.A ‘polyp’ is any elevation above the surface of the lining of the gut (the mucosa). Polyps can range in size from several millimetres to up to 10 cm in size. Polyps can be found on their own, or in multiples (in particular in the hereditary syndromes). The importance of polyps, is that some of them (in particular adenomas) have malignant potential – the potential to lead to colorectal cancer. Polyps can thus be separated into non-neoplastic, and neoplastic.  Non-neoplastic: ‘Hamartomatous’ – meaning of an unusual make-up – include ‘juvenile’ polyps, and the polyps found in Peutz-Jeghers syndrome. Neoplastic: Adenomas – may be single, or multiple. In familial adenomatous polyposis (FAP) there are more than a hundred.

Statistics on Colonic polyps and hereditary polyposis syndromes

Approximately 1 in 10,000 of people have the mutant APC gene responsible for Familial Adenomatous Polyposis (FAP). There are a couple of variants of FAP – Gardner’s syndrome, and Turcot’s syndrome, but they involve the same gene. Non-adenomatous polyposis syndromes are rare.

Risk Factors for Colonic polyps and hereditary polyposis syndromes

The familial conditions, both the non-neoplastic ones (Juvenile polyposis, Peutz-Jeghers) and the neoplastic (FAP) are all autosomal dominant. That means that a person needs only one abnormal gene (from either parent) to have the disorder – hence they are passed on very easily. More commonly, however, colonic adenomas may occur without a genetic predisposition in any other person. In fact most people with adenomas (which are usually the precursor to colon cancer) do not have a genetic syndrome like the above.

Progression of Colonic polyps and hereditary polyposis syndromes

Individuals with FAP will almost inevitably develop colon cancer during their thirties. There is also an increased risk of other gastrointestinal malignancies such as adenocarcinoma of the duodenum and gastric and ileal adenocarcinomas.

Peutz-Jeghers is associated with a slightly increased risk of development of small and large bowel cancers, as well as other tumours – of the ovary and pancreas. Juvenile polyposis is associated with an increased risk of colorectal cancer.

How is Colonic polyps and hereditary polyposis syndromes Diagnosed?

  • Full blood count: There may be anaemia if there has been rectal blood loss.
  • PR (rectal) exam: May reveal a rectal polyp or carcinoma.

Prognosis of Colonic polyps and hereditary polyposis syndromes

As mentioned above, individuals with FAP who are not screened and treated early will develop colon cancer in their thirties, which can be fatal. However, with early screening and prophylactic removal of the colon (colectomy) in their twenties, many individuals are now able to live normal life spans. The prognosis for the other syndromes will depend on whether affected individuals do actually develop colon cancer (or another type) – otherwise there is no effect on prognosis.

How is Colonic polyps and hereditary polyposis syndromes Treated?

Adenomatous Polyposis Syndromes: Prophylactic removal of the colon is needed. Two options are possible: The whole colon can be removed (proctocolectomy) which means the patient needs a stoma (an ileostomy bag-An ileostomy provides a new path for waste material to leave the body after part of the intestine has been removed), but there is no chance of developing colon cacer. Alternatively, the colon without the rectum can be removed (colectomy) which means the patient does not need a stoma, but the patient needs to be followed up (with proctoscopy) to make sure they do not develop rectal cancer. Surgery is performed in the patient’s twenties. Regular follow-up with an upper endoscopy (a thin flexible instrument is advanced through the mouth to evaluate or treat problems of the oesophagus, stomach, and beginning part of the small intestine) is recommended when an individual is in their fifties because of the risk of cancer in the upper GI tract – mainly the duodenum. The patient’s family members should be screened after the age of twelve.  

Non-Adenomatous Polyposis Syndromes: Children of an affected individual may have a screening sigmoidoscopy ( Inspection of the rectum and lower colon using a thin lighted tube called a sigmoidoscope). If it is found to have hamartomatous polyps they are at increased risk for obstruction of bleeding. Polyps should be removed at the time of sigmoidoscopy.

Colonic polyps and hereditary polyposis syndromes References

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