3. Familial Polyposis of the Colon

Familial Polyposis of the Colon

This PatientPlus article is written for healthcare professionals so the language may be more technical than the condition leaflets. You may find the abbreviations list helpful.

Synonyms: familial adenomatous polyposis (FAP), familial polyposis coli.

Familial polyposis of the colon causes widespread development of adenomas in the colon and rectum. The number of polyps can range from no detectable polyps at colonoscopy to more than 7,000 seen on resected specimens of bowel. The polyposis predominantly affects the distal colon (80-90%).[1]

Attenuated familial adenomatous polyposis[2]

Attenuated familial adenomatous polyposis (AFAP) is characterised by fewer colonic polyps (100 or less) and a delayed onset of symptoms and complications. The colonic polyps tend to involve the proximal colon and spare the rectum.

  • The true incidence of AFAP is not known.
  • There is a delay in onset of adenomatosis and bowel symptoms of 20-25 years, a delay in onset of colorectal cancer of 10-20 years and a delay in death from colorectal cancer of 15-20 years.
  • Because of the tendency to affect the proximal colon, colonoscopy is preferred to sigmoidoscopy for surveillance, which should begin at the age of 20-25 years.
  • There are often associated gastric and duodenal adenomas, and so regular upper gastrointestinal endoscopy is also recommended.

Gardner's syndrome is characterised by colonic polyposis with osteomas and soft tissue tumours. Turcot's syndrome is the association of colonic polyposis and tumours of the central nervous system.[3] In 1951 Gardner described the occurrence of FAP with the extracolonic manifestations of desmoids, osteomas and epidermoid cysts.

  • The incidence of familial polyposis of the colon is between 1 in 8,300 and 1 in 14,025 live births.[4]
  • Colonic polyps begin developing at a mean age of 16 years (range 7-36 years).[3]
  • Familial polyposis syndromes have autosomal dominant inheritance with almost complete penetrance but marked variation in expression.[5] Mutations of the APC gene on chromosome 5 are thought to be responsible.[6]
  • The location of the mutation on the gene is thought to influence the nature of the extracolonic manifestations.[4]

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  • Adenomas usually begin to develop during the second decade of life.
  • Unfortunately it often presents with colorectal cancer.
  • The median age at diagnosis is 40.[6]

Symptoms

  • Patients are often asymptomatic, but may present with rectal bleeding, diarrhoea, abdominal pain and mucous discharge.[4]
  • Obstruction may cause constipation, vomiting and peritonitis.
  • Dental abnormalities may cause jaw pain.
  • Gastric polyps may cause epigastric pain or bleeding.
  • Duodenal polyps may cause pain, bleeding or obstructive jaundice.
  • Polyps in the ileum may cause obstruction.
  • Thyroid carcinoma may present as a neck mass, pain, hoarseness and features of hypothyroidism or hyperthyroidism.

Signs

  • Rectal polyps or masses.
  • Other commonly associated features:[6]
    • Congenital hypertrophy of the retinal pigment epithelium (CHRPE) - evaluated by slit-lamp examination and indirect ophthalmoscopy - which can be an useful early clue as to whether the patient is a carrier of the APC gene.
    • Dental problems - supernumerary teeth, odontomas, non-erupted teeth.
    • Epidermoid cysts.
    • Desmoid tumours or osteomas (skull, endosteal and exosteal osteomas).
    • Thyroid masses.
  • Full blood count.
  • Carcinoembryonic antigen testing: raised levels may indicate colorectal carcinoma.
  • Liver function tests to evaluate possible metastasis.
  • Thyroid function tests.
  • Faecal occult blood.
  • CT or MRI scan of the abdomen and pelvis.
  • Dental X-rays, chest X-ray and skull X-ray (for jaw lesions, osteomas, supernumerary teeth).
  • Colonoscopy with biopsies: investigation of choice for diagnosis.
  • Upper gastrointestinal endoscopy: for evaluation of gastric and duodenal polyps.
  • Genetic testing: for the APC gene and its mutation. Prenatal testing is possible if a disease-causing mutation is identified in an affected family member.

Other hereditary polyposis syndromes:[5]

The majority of patients have one or more extracolonic features.[6][7] Extracolonic features include:[4]

  • Malignant tumours:
  • Nasopharyngeal angiofibromas
  • Osteomas
  • Radiopaque jaw lesions
  • Supernumerary teeth
  • Lipomas, fibromas, epidermoid cysts
  • Desmoid tumours
  • Gastric adenomas
  • Duodenal, jejunal and ileal adenomas

Screening by flexible sigmoidoscopy with biopsy of polyps for histological diagnosis confirms the condition and allows surgery before the age of 20.

  • A regression of polyps and biochemical markers has been reported with cyclo-oxygenase inhibitors. There is evidence that low-dose aspirin significantly reduces the recurrence of adenomatous polyps after 1 to 3 years.[8] Sulindac is recommended in patients with rectal polyps following total colectomy.
  • Tamoxifen has also been recommended.
  • Sulindac, tamoxifen, or a combination of both, are recommended for desmoid polyps of the abdominal wall or for extra-abdominal manifestations of the disease.

Surgical

The types of surgery are:[9]

  • Proctocolectomy with ileostomy
  • Total colectomy with ileorectal anastomosis
  • Restorative proctocolectomy with ileo pouch anal anastomosis is the main surgical treatment for patients with FAP.[10][11][12]

Complications secondary to polyps lining the colon include:

  • Gastrointestinal haemorrhage.
  • Gastrointestinal obstruction.
  • Malignant change (if prophylactic colectomy is not performed). The risk of colorectal cancer increases with the number of polyps:
    • By age 35 years, 95% of affected individuals have polyps and, without colectomy, colon cancer is inevitable.[3]
    • The mean age of colon cancer diagnosis in untreated individuals is 39 years (range 34-43 years).[3]
    • Patients with more than 1,000 polyps have been proven to have 2.3 times the cancer risk compared to patients with fewer than 1,000 polyps.
    • The cancer risk increases 2.4 times for every 10 years of polyps.[1]
  • Colon cancer will develop in all affected individuals unless prophylactic colectomy is performed.
  • After total colectomy with ileorectal anastomosis, the recurrence rate is 30% after 20 years and 45% after 30 years.

Screening family members by flexible sigmoidoscopy confirms or eliminates the diagnosis.

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Further reading & references

  1. Debinski HS, Love S, Spigelman AD, et al; Colorectal polyp counts and cancer risk in familial adenomatous polyposis. Gastroenterology. 1996 Apr;110(4):1028-30.
  2. Knudsen AL, Bisgaard ML, Bulow S; Attenuated familial adenomatous polyposis (AFAP). A review of the literature. Fam Cancer. 2003;2(1):43-55.
  3. Gene Reviews; Familial polyposis coli
  4. Nandakumar G et al; Familial polyposis coli: clinical manifestations, evaluation, management and treatment. Mt Sinai J Med; 2004 Nov;71(6):384-91.
  5. Luk GD; Diagnosis and therapy of hereditary polyposis syndromes. Gastroenterologist. 1995 Jun;3(2):153-67.
  6. Familial Polyposis Coli, Online Mendelian Inheritance in Man (OMIM)
  7. Krush AJ, Traboulsi EI, Offerhaus JA, et al; Hepatoblastoma, pigmented ocular fundus lesions and jaw lesions in Gardner syndrome. Am J Med Genet. 1988 Feb;29(2):323-32.
  8. Asano TK, McLeod RS; Non steroidal anti-inflammatory drugs (NSAID) and Aspirin for preventing colorectal adenomas and carcinomas. Cochrane Database Syst Rev. 2004;(2):CD004079.
  9. Campos FG, Habr-Gama A, Kiss DR, et al; Extracolonic manifestations of familial adenomatous polyposis: incidence and impact on the disease outcome. Arq Gastroenterol. 2003 Apr-Jun;40(2):92-8. Epub 2004 Jan 16.
  10. Ahmed Ali U, Keus F, Heikens JT, et al; Open versus laparoscopic (assisted) ileo pouch anal anastomosis for ulcerative colitis and familial adenomatous polyposis. Cochrane Database Syst Rev. 2009 Jan 21;(1):CD006267.
  11. Ambroze WL Jr, Dozois RR, Pemberton JH, et al; Familial adenomatous polyposis: results following ileal pouch-anal anastomosis and ileorectostomy. Dis Colon Rectum. 1992 Jan;35(1):12-5.
  12. Kartheuser AH, Parc R, Penna CP, et al; Ileal pouch-anal anastomosis as the first choice operation in patients with familial adenomatous polyposis: a ten-year experience. Surgery. 1996 Jun;119(6):615-23.
Original Author: Dr Colin Tidy Current Version:
Last Checked: 18/03/2011 Document ID: 2134  Version: 22 © EMIS

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.