Genetics of Colorectal Cancer (PDQ®): Genetics - Health Professional Information [NCI] - Major Genetic Syndromes
Table 8. Clinical Practice Guidelines for Diagnosis and Colon Surveillance of Familial Adenomatous Polyposis (FAP)
|Organization||APCGene Test Recommended||Age Screening Initiated||Frequency||Method||Comment|
|C = colonoscopy; FS = flexible sigmoidoscopy; GI = gastrointestinal; NA = not addressed; NCCN = National Comprehensive Cancer Network.|
|a GI Societies – American Academy of Family Practice, American College of Gastroenterology, American College of Physicians-American Society of Internal Medicine, American College of Radiology, American Gastroenterological Association, American Society of Colorectal Surgeons, and American Society for Gastrointestinal Endoscopy.|
|American Society of Colon and Rectal Surgeons (2001, 2003)[140,141,142]||Yes||NA||NA||NA|| |
|American Cancer Society (2002)||NA||Puberty||NA||Endoscopy||Referral to a center specializing in FAP screening suggested.|
|GI Societies (2003)a||Yes||10–12 y||Annual||FS|| |
|NCCN (2014)||Yes||10–15 y||Annual||FS or C||ConsiderMYHmutation testing ifAPCtesting is negative and family history is compatible with recessive inheritance; in families in which no mutation is found, offspring of those affected are screened as if they were carriers.|
Once an FAP family member is found to manifest polyposis, colectomy is the only effective management. Patient and doctor should enter into an individualized discussion to decide when surgery should be performed. It is useful to incorporate into the discussion the risk of developing desmoid tumors after surgery. Timing of risk-reducing surgery usually depends on the number of polyps, their size, histology, and symptomatology. Once numerous polyps have developed, surveillance colonoscopy is no longer useful in timing the colectomy because polyps are so numerous that it is not possible to biopsy or remove all of them. At this time, it is appropriate for patients to consult with a surgeon who is experienced with available options, including total colectomy and postcolectomy reconstruction techniques. Rectum-sparing surgery, with sigmoidoscopic surveillance of the remaining rectum, is a reasonable alternative to total colectomy in those compliant individuals who understand the consequences and make an informed decision to accept the residual risk of rectal cancer occurring despite periodic surveillance.
Surgical options include restorative proctocolectomy with IPAA, subtotal colectomy with ileorectal anastomosis (IRA), or total proctocolectomy with ileostomy (TPC). TPC is reserved for patients with low rectal cancer in which the sphincter cannot be spared or for patients on whom an IPAA cannot be performed because of technical problems. There is no risk of developing rectal cancer after TPC because the whole mucosa at risk is removed. Whether a colectomy and an IRA or a restorative proctocolectomy is performed, most experts suggest that periodic and lifelong surveillance of the rectum or the ileal pouch be performed to remove or ablate any polyps. This is necessitated by case series of rectal cancers arising in the rectum of FAP patients who had subtotal colectomies with an IRA in which there was an approximately 25% cumulative risk of rectal adenocarcinoma 20 years after IRA and by case reports of adenocarcinoma in the ileoanal pouch and anal canal after restorative proctocolectomy.[147,148,149,150] The cumulative risk of rectal cancer after IRA may be lower than that reported in the literature, in part because of better selection of patients for this procedure, such as those with minimal polyp burden in the rectum. Other factors that have been reported to increase the rectal cancer risk after IRA include the presence of colon cancer at the time of IRA, the length of the rectal stump, and the duration of follow-up after IRA.[151,152,153,154,155,156,157] An abdominal colectomy with IRA as the primary surgery for FAP does not preclude later conversion to an IPAA for uncontrolled rectal polyps and/or rectal cancer. In the Danish Polyposis Registry, the morbidity and functional results of a secondary IPAA (after a previous IRA) in 24 patients were reported to be similar to those of 59 patients who underwent primary IPAA.