ACG Updates the Diagnosis and Management of Adenomatous Colorectal Polyposis Syndromes: AJG | September 2026

Introduction:

Hereditary adenomatous polyposis syndromes are systemic cancer-predisposition disorders involving not only the colorectum but also the stomach, duodenum and other organs. The updated ACG guideline emphasises earlier genetic recognition, multigene testing, structured surveillance and individualised endoscopic or surgical management.

Why Is This Guideline Important?

Phenotypic overlap between FAP, attenuated FAP (AFAP), MUTYH-associated polyposis (MAP), polymerase proofreading-associated polyposis (PPAP) and rarer syndromes makes phenotype alone insufficient. Genetic diagnosis can guide both the patient's management and surveillance of relatives.

Key Takeaways:

≥20 cumulative colorectal adenomas is a strong trigger for germline testing; testing may also be considered with 10–19 adenomas.

Extracolonic FAP manifestations—including desmoid tumors, multifocal/bilateral CHRPE, hepatoblastoma and cribriform-morular thyroid carcinoma—should also trigger genetic evaluation.

Use multigene panel testing, including APC, MUTYH, POLE/POLD1 and other relevant polyposis/cancer-predisposition genes.

A negative panel does not end the evaluation. Colonic polyposis of uncertain etiology should be managed according to adenoma burden, and APC mosaicism testing should be considered.

Start colorectal surveillance early: approximately 10–15 years for FAP, 18–20 years for AFAP/MAP, and 25–30 years for PPAP, generally every 1–3 years.

During colonoscopy, remove adenomas ≥10 mm and ≥4 mm when feasible.

Multifocal high-grade dysplasia, unmanageable polyp burden, polyposis-related symptoms or colorectal cancer should prompt surgical referral.

Gastric surveillance should document fundic gland polyps, gastric adenomas, white mucosal patches, polypoid mounds and carpeting. Gastric adenomas should be resected; multifocal HGD or adenocarcinoma may require gastrectomy.

Duodenal disease should be graded using the Spigelman score, incorporating polyp number, size, histology and dysplasia.

Upper-GI surveillance intervals should follow whichever is more severe—gastric or duodenal polyposis.

Bottom Line:

Modern polyposis management is increasingly genotype-directed. Recognize the adenoma burden early, perform appropriate multigene germline testing, actively survey both the colorectum and upper GI tract, and individualize surgery according to cancer risk and whether the polyp burden remains endoscopically manageable.