What is the management plan for gastric polyposis?

Management of Gastric Polyposis

The management of gastric polyposis depends critically on the underlying syndrome: for hereditary polyposis syndromes (FAP, GAPPS, JPS), initiate upper endoscopy surveillance at age 18-30 years with 1-3 yearly intervals based on genetic mutation and polyp burden; for sporadic fundic gland polyps, conservative management with biopsy of atypical lesions is appropriate; and all adenomas require complete resection with annual surveillance thereafter. 1

Initial Diagnostic Approach

Document polyp characteristics systematically: Record the number (or estimated number), location, and size of the largest polyp with photographic documentation of all polyps or representative samples if numerous 1. Enhanced endoscopic imaging (NBI, FICE, i-Scan) should be used when diagnostic uncertainty exists after white light examination 1.

Biopsy strategy varies by polyp type:

• All gastric polyps except fundic gland polyps (FGPs) require biopsy for histopathological assessment 1
• When adenomas or hyperplastic polyps are present, assess the background mucosa for gastric atrophy, intestinal metaplasia, H. pylori, and synchronous neoplasia 1
• FGPs are typically multiple, small (<1 cm), pale, smooth, and translucent with lacy blood vessels visible through the surface 1

Syndrome-Specific Management

Familial Adenomatous Polyposis (FAP)

Upper GI surveillance timing:

• Begin upper endoscopy at age 25-30 years when colorectal polyposis is diagnosed, whichever comes first 1
• Use side-viewing endoscope with Spigelman staging and extensive biopsy of dense lesions 1
• Surveillance intervals based on Spigelman stage: Stage 0 every 4 years, Stage I every 2-3 years, Stage II every 1-3 years, Stage III every 6-12 months, Stage IV requires expert surveillance every 6-12 months with surgical evaluation 1

Critical warning: Western FAP patients show an alarming increase in proximal gastric cancer, often diagnosed at advanced stages despite regular surveillance, as fundic gland polyposis carpeting hampers visualization 2. More intensive surveillance and treatment are required in patients with large or villous adenomas and advancing age >50 years 1.

Endoscopic treatment options include:

• Endoscopic papillectomy for duodenal papilla lesions 1
• Excision or ablation of large (>1 cm) or villous adenomas 1
• Mucosectomy of resectable advanced lesions including contained high-grade dysplasia 1

Surgery is indicated for:

• Invasive carcinoma 1
• Dense polyposis or high-grade dysplasia unmanageable endoscopically 1
• Surgical options include duodenectomy or Whipple procedure if duodenal papilla is involved 1

Gastric Adenocarcinoma and Proximal Polyposis of the Stomach (GAPPS)

Surveillance protocol:

• Upper endoscopy surveillance starting at age 25-30 years 1
• Continue every 1-5 years based on polyp burden 1
• GAPPS is characterized by extensive fundic gland polyps in fundus/body, sparing antrum and lesser curvature, with significant gastric adenocarcinoma risk 3

Critical consideration: Recent reports describe metastatic cancer or invasive adenocarcinoma development after variable surveillance periods, emphasizing the need for vigilant monitoring 3. Prophylactic total gastrectomy should be considered in high-risk cases 3.

Juvenile Polyposis Syndrome (JPS)

Upper GI surveillance is mutation-specific:

• SMAD4 mutation carriers: Begin upper endoscopy at age 18 years with 1-3 yearly intervals personalized to upper GI tract phenotype 1
• BMPR1A mutation carriers: Begin at age 25 years with 1-3 yearly intervals 1
• No identified mutation: Upper GI screening not required routinely but initiate when clinical diagnosis is made based on colonic phenotype 1

SMAD4-specific risks:

• 73% vs 8% risk of gastric polyposis compared to BMPR1A carriers (p<0.001) 1
• All gastric cancers in one cohort occurred in SMAD4 mutation carriers 1
• Evaluate for hereditary hemorrhagic telangiectasia (HHT) in all SMAD4 carriers, as up to 76% have HHT features 1
• Manage in conjunction with specialist HHT center due to risk of asymptomatic arteriovenous malformations 1

Gastric phenotype in JPS:

• Exclusively gastric JPS presents as mixed hypertrophic and polypoid gastropathy with abundant adherent mucus 4
• Initially misdiagnosed as hyperplastic polyps; macrobiopsy specimens and SMAD4 testing confirm diagnosis 4

MUTYH-Associated Polyposis (MAP)

Upper GI surveillance:

• Begin at age 35 years 1
• Surveillance intervals determined as outlined for FAP using Spigelman classification 1
• Biallelic MUTYH mutations suspected in AFAP/FAP with recessive inheritance pattern and diagnosis before age 50 years 1

Management by Polyp Type

Fundic Gland Polyps (FGPs)

Conservative management for sporadic FGPs:

• Most prevalent gastric polyp type (13-77%) 1
• Typically benign with minimal malignancy risk unless FAP-associated 1, 5
• Larger FGPs (>1 cm) may harbor dysplasia and warrant biopsy 1
• FAP-associated FGPs require closer surveillance due to dysplastic potential 5

Adenomatous Polyps

Mandatory resection protocol:

• All adenomas must be resected when clinically appropriate and safe 1
• Follow-up gastroscopy at 12 months after complete endoscopic excision 1
• Annual surveillance gastroscopy thereafter when appropriate 1

Background assessment: When adenomas are present, endoscopically assess for gastric atrophy, intestinal metaplasia, H. pylori, and synchronous neoplasia 1.

Hyperplastic Polyps

Selective resection criteria:

• Resect if >1 cm, pedunculated morphology, or causing symptoms (obstruction, bleeding) 1
• Eradicate H. pylori before re-evaluation for endoscopic therapy 1

Special Populations

Patients with Microdeletions Involving BMPR1A and PTEN

Refer to local genetics center for coordinated surveillance addressing both JPS and PTEN-hamartoma tumor syndrome (PHTS) manifestations 1.

Family History Without Identified Mutation

For first-degree relatives with clinical JPS diagnosis but no identified mutation, upper GI screening is not routine but should be initiated when colonic phenotype establishes clinical diagnosis 1. Consider earlier screening if family history suggests HHT even without colonic polyps 1.

Common Pitfalls to Avoid

Do not apply HDGC protocols to all gastric polyposis cases: Hereditary diffuse gastric cancer requires distinct management with CDH1 testing and consideration of prophylactic gastrectomy 6, 7. This is fundamentally different from polyposis syndrome management.

Do not delay genetic testing in multiple adenoma cases: Patients with >10 colorectal adenomas require panel germline testing including APC, MUTYH, POLE, POLD1, and NTHL1 genes, with APC analysis including large rearrangements 1.

Do not underestimate SMAD4-associated gastric cancer risk: The significantly elevated risk in SMAD4 carriers (versus BMPR1A) mandates earlier surveillance initiation and consideration of more aggressive management 1.

Do not miss H. pylori assessment: All individuals with family history of gastric cancer who test positive for H. pylori require eradication therapy and confirmation of eradication 7.