A working group put together by the American Society for Gastrointestinal Endoscopy (ASGE) released recommendations based on emerging evidence and expert opinion for the role of endoscopy in the management of patients with familial adenomatous polyposis (FAP) syndromes. Their report was published in Gastrointestinal Endoscopy.
The investigators performed a systematic review of literature published between January 2005 and May 2018, focused on evidence supporting the use of endoscopy in FAP syndromes, including attenuated FAP and MUTYH-associated polyposis (MAP). Recommendations were developed based on the quality of evidence and anticipated benefit and harm.
Recommendations for Genetic Counseling and Testing
The ASGE recommends genetic counseling and testing for all patients with or suspected to have FAP syndromes. Genetic testing for mutations in the adenomatous polyposis coli (APC) gene is recommended to confirm a diagnosis of FAP in patients with a family history of FAP syndromes, for those with at least 10 adenomas identified on a single endoscopic examination, and for those with at least 20 adenomatous polyps identified in their lifetime.
Genetic counseling is recommended for all first-degree relatives of patients with confirmed polyposis syndrome. As the development of colorectal cancer is rare in younger children, the ASGE recommends APC gene testing and screening examinations for children starting at the age of 10 to 12 years. If attenuated FAP or MAP are suspected, individuals should undergo genetic testing starting at the age of 18 to 20 years.
Recommendations for Endoscopy in FAP
In children with suspected FAP, screening should start at 10 to 12 years of age; sigmoidoscopy is adequate for screening purposes. If no polyps are found on initial sigmoidoscopy, the patient should be offered follow-up screening every 2 years, starting in the late teens. If children present with polyps in the rectosigmoid colon, complete colonoscopy is recommended to assess the severity of polyposis and to resect large polyps.
In confirmed FAP, surveillance colonoscopy can reduce the risk of colorectal cancer in patients with a manageable polyp burden and is recommended at 1- to 2-year intervals. Screening intervals can be gradually extended if no adenomas are detected.
Recommendations for Endoscopy in Attenuated FAP
There is limited evidence on screening recommendations for attenuated FAP (AFAP). Because AFAP is characterized by a later onset of polyps and a lower risk of colorectal cancer, the ASGE recommends a screening colonoscopy for patients with or suspected of having AFAP starting at the age of 18 to 20 years. Sigmoidoscopy is considered inadequate as patients may not develop rectal polyps.
In patients with confirmed AFAP, surveillance colonoscopy with polypectomy is recommended at 1- to 2-year intervals as it may prevent the need for future surgery in patients with low polyp burden.
Recommendations for Endoscopy in MAP
Similar to AFAP, MAP is associated with later onset colorectal cancer and rectal involvement is uncommon; therefore, screening colonoscopy is recommended for patients with or suspected of having MAP starting at the age of 18 to 20 years.
Patients with low polyp burden can be adequately managed with polypectomy, and the ASGE recommends surveillance colonoscopy in patients with MAP at intervals of 1 to 2 years. Once colorectal cancer is diagnosed or the polyp burden becomes unmanageable, patients should undergo subtotal colectomy.
Recommendations for Endoscopy in Patients With IPAA or IRA
For patients with a rectal polyp burden greater than 20, large polyps (>1 cm in size), or advanced histology, colectomy with ileal pouch-anal anastomosis (IPAA) is recommended as an appropriate intervention. Colectomy with ileorectal anastomosis (IRA) may be an option for patients with preoperative or rectal-sparing endoscopic rectal clearance.
Surveillance after surgery is necessary due to the increased risk for adenomas in the ileum, rectal cuff, and anal transition zone. The ASGE recommends endoscopy of the pouch or ileoscopy in patients with IPAA at 1- to 2-year intervals, while patients with IRA should undergo sigmoidoscopy at 6-month to 1-year intervals indefinitely.
Recommendations for Endoscopy in the Upper GI Tract
Fundic gland polyps are common in patients with FAP and often arise in adolescence; up to 42% of fundic gland polyps are associated with dysplasia, although they rarely develop into adenocarcinoma. Screening and surveillance endoscopy are recommended and include random biopsy sampling of suspicious lesions and complete resection of polyps measuring >1 cm to assess for dysplasia and malignancy.
Gastric adenomas can occur anywhere in the stomach but occur most frequently in the antrum; however, antral adenomas are often more subtle than other fundic gland polyps. Therefore, the ASGE recommends endoscopists practice a high degree of suspicion with a low threshold to biopsy and resect all antral polyps.
The incidence of duodenal adenomas in patients with FAP is >90%, and duodenal involvement typically begins early. The severity of duodenal polyposis increases with age, and a baseline Spigelman score ≥7 is a risk factor for development of high-grade dysplasia. Endoscopic management is recommended to identify and follow patients with duodenal polyposis in order to assess for dysplasia and accurate Spigelman stage.
In patients with high-grade dysplasia, Spigelman stage III or IV duodenal polyposis, or polyps measuring >1 cm, the goal is to downstage the disease with strict endoscopic surveillance and resection of high-risk polyps. Because 50% of duodenal adenomas occur in the ampullary region, the ASGE recommends careful examination of this area using a side-viewing duodenoscope or a cap-assisted upper endoscope. Given the potential risk for pancreatitis, special attention should be paid to avoid the pancreatic orifice.
Recommendations for Chemoprevention
Chemopreventive agents have the theoretical advantage of reducing adverse effects in patients with FAP, but data are still emerging regarding their clinical application. The ASGE recognizes the potential efficacy of chemoprevention and recommends it within the confines of a clinical trial or a hereditary cancer center.
Disclosure: Multiple authors declared affiliations with the pharmaceutical industry. Please see original reference for a complete list of authors’ disclosures.
Yang J, Gurudu SR, Koptiuch C, et al. American Society for Gastrointestinal Endoscopy guideline on the role of endoscopy in familial adenomatous polyposis syndromes [published online March 10, 2019]. Gastrointest Endosc. doi:10.1016/j.gie.2020.01.028