What is the management and surveillance plan for serrated polyps?

Management and Surveillance of Serrated Polyps

Risk Stratification and Surveillance Intervals

For serrated polyps ≥10 mm or any serrated lesion with dysplasia (including traditional serrated adenomas), offer a one-off surveillance colonoscopy at 3 years. 1, 2

High-Risk Serrated Lesions (3-Year Surveillance)

• Sessile serrated lesions (SSLs) ≥10 mm require 3-year surveillance colonoscopy due to their association with advanced neoplasia and predictive value for colorectal cancer (CRC). 1, 2 These larger lesions are associated with dysplasia and have a mean progression interval of approximately 15 years from SSL without dysplasia to cancer. 1

• Any serrated lesion harboring dysplasia (including sessile serrated polyps with cytologic dysplasia) should be managed like high-risk adenomas with 3-year surveillance. 1, 2 These lesions represent more advanced stages in the polyp-cancer sequence. 3

• Traditional serrated adenomas (TSAs) of any size warrant 3-year surveillance regardless of size or location. 1, 2

• Multiple small SSLs: Patients with 3-4 SSPs <10 mm require 3-5 year surveillance, while those with 5-10 SSPs <10 mm require 3-year surveillance. 2

Low-Risk Serrated Lesions (No Routine Surveillance)

• Small hyperplastic polyps (<10 mm) in the rectosigmoid are not risk markers for future CRC and require no surveillance beyond routine 10-year screening intervals. 1, 2

• Small proximal serrated lesions (<10 mm without dysplasia) have no clear indication for colonoscopic surveillance unless they meet criteria for serrated polyposis syndrome (SPS). 1, 2 The evidence for these lesions as risk markers remains unclear, with most risk associated with larger lesions. 1

• Patients with nonadvanced serrated polyps showed no significant increase in CRC risk compared to those without polyps (HR 1.25; 95% CI 0.76-2.08). 4

Serrated Polyposis Syndrome (SPS)

Patients meeting WHO criteria for SPS require intensive 1-2 yearly colonoscopic surveillance due to substantially elevated CRC risk that can be reduced through effective surveillance. 1, 2

WHO 2019 Criteria for SPS:

• At least 5 serrated polyps proximal to sigmoid colon, with 2 being >10 mm in diameter 1
• More than 20 serrated polyps of any size distributed throughout the colon 1

Note: The criterion for first-degree relatives with serrated polyps was abandoned in the 2019 WHO definition. 1

SPS Management Algorithm:

1. Initial clearing colonoscopy: Remove all polyps ≥3 mm to achieve complete clearance. 5 Successful endoscopic clearance can be achieved in approximately 82% of patients. 5

2. Surveillance interval: Once larger polyps are removed (only polyps ≤5 mm remaining), initiate surveillance every 1-2 years. 1 Annual surveillance prevents CRC development without significant morbidity, with 0% CRC incidence during follow-up in prospective studies. 5

3. Surgical consideration: Surgery should be considered when lesions are not amenable to colonoscopic resection due to size, site, or number. 1, 2 Options include segmental colectomy, total colectomy with ileorectal anastomosis, or proctocolectomy depending on lesion burden and distribution. 1

4. Genetics referral: All SPS patients should be referred to clinical genetics services or a polyposis registry where resources allow. 1, 2

5. Family screening: First-degree relatives of SPS patients should undergo colonoscopic screening every 5 years starting at age 40 or 10 years before the index case diagnosis, due to a 3-5 fold increased standardized incidence ratio for CRC. 1, 6

Resection Techniques and Post-Resection Management

Piecemeal Resection Follow-up:

• For serrated lesions ≥20 mm resected piecemeal: Perform examination of the resection site within 2-6 months post-resection. 1, 2 Recurrence rates for SSPs ≥20 mm are approximately 7% at 12 months (lower than adenomas at 20%, but still significant). 1

• For lesions 10-20 mm resected piecemeal: Endoscopist discretion is advised regarding whether a 2-6 month site check is required versus standard surveillance intervals, depending on patient factors and assessment of complete excision likelihood. 1

Important Resection Considerations:

• Cold snare resection is preferred for proximal colon lesions <10 mm. 3

• En bloc resection should be attempted whenever possible for polyps <20 mm to allow proper pathologic assessment. 1, 7

• Incomplete resection is a major concern, with up to 50% of large SSPs potentially removed incompletely with standard techniques, contributing to interval cancer risk. 3

Combined Adenoma and Serrated Polyp Findings

When both adenomas and serrated polyps are present, consider each polyp group separately for surveillance—the shortest surveillance interval recommended should take precedence. 1 There is no current data suggesting that risk is cumulative. 1

Patients with baseline advanced adenomas and proximal SSPs are more likely to have advanced neoplasia at follow-up compared to those with tubular adenomas alone. 1

Quality Benchmarks

• Proximal serrated polyp detection rate: Endoscopists should aim for >5% detection rate, though this is challenging and affected by case mix, patient ethnicity, and histopathological diagnosis. 1, 2

• Clinician competency: All clinicians involved in serrated polyp care, especially endoscopists and pathologists, must acquire knowledge and skills to recognize and differentiate various types of serrated lesions. 1, 2 These lesions have distinct endoscopic appearances and are more difficult to detect than conventional adenomas. 2, 3

Critical Pitfalls to Avoid

• Pathologic misclassification: Significant interobserver variation exists in pathologic interpretation between hyperplastic polyps and SSPs, particularly for smaller lesions. 1, 3 Some experts recommend considering all proximal colon serrated lesions ≥10 mm as sessile serrated polyps even if pathology reports hyperplastic polyp. 1

• Inadequate surveillance for multiple small polyps: Patients with multiple serrated polyps not meeting SPS criteria may still have elevated CRC risk and warrant closer surveillance than standard 10-year intervals. 1

• Incomplete resection: The flat morphology of SSPs makes them difficult to grip and resect completely, requiring specialized techniques and expertise for lesions ≥10 mm. 3, 6