What is the recommended interval for repeating colonoscopy in patients with serrated polyposis syndrome (SPS)?

Colonoscopy Surveillance Intervals for Serrated Polyposis Syndrome

Patients with serrated polyposis syndrome (SPS) should have colonoscopic surveillance yearly once the colon has been cleared of all lesions >5 mm in size, with the interval extended to 2 years if no polyps ≥10 mm are identified at subsequent surveillance examinations. 1

Diagnosis and Initial Management

The diagnosis of SPS should be made according to the WHO 2019 criteria, which include:

1. At least five serrated polyps proximal to the sigmoid colon, two of which are >10 mm in diameter
2. Any number of serrated polyps occurring proximal to the sigmoid colon in an individual who has a first-degree relative with serrated polyposis
3. More than 20 serrated polyps of any size distributed throughout the colon 1

Initial Clearing Phase

• A high-quality colonoscopy with pancolonic dye spray is recommended to accurately define the polyp phenotype 1
• Complete removal of all polyps >5 mm is essential before entering the surveillance phase
• Achieving control typically requires:
  • 2-3 colonoscopies over 1-2 years 2
  • A mean of 27.9 polyp resections during the clearing phase 2

Surveillance Protocol

Surveillance Intervals

• First year after clearing: Annual colonoscopy is recommended for all SPS patients 1
• Subsequent surveillance:
  • Continue annual surveillance if polyps ≥10 mm are found 1
  • Extend to 2-year intervals if no polyps ≥10 mm are identified at subsequent examinations 1

Rationale for Surveillance Intervals

The recommended surveillance intervals are based on:

1. The high risk of metachronous polyp development (all patients develop additional polyps during surveillance) 3
2. The risk of colorectal cancer (CRC) development, which can be effectively reduced through intensive surveillance 1
3. Evidence showing that extending intervals to 24 months is safe for patients who achieve control of polyp burden 2

Special Considerations

Risk Stratification

• Higher risk features requiring more vigilant surveillance:
  • Polyps ≥10 mm
  • Serrated lesions with dysplasia
  • Traditional serrated adenomas (TSAs)
  • Inability to clear all polyps >5 mm

Surgical Management

Consider surgical referral when:

• Polyp burden cannot be controlled endoscopically
• Patients requiring multiple short-interval colonoscopies (≤12 months) for control 4
• Patients with persistently high polyp counts (≥20 pancolonic polyps) after four procedures 4

Effectiveness of Surveillance

Evidence supports that proper surveillance effectively prevents CRC:

• Studies show no incident cancers during surveillance periods when appropriate intervals are maintained 2, 4
• Most patients (96%) can be successfully managed with colonoscopy alone without requiring surgery 4
• After the fourth colonoscopy, most patients managed endoscopically (86%) have <10 pancolonic polyps and >90% no longer have proximal serrated polyps ≥10mm 4

Family Screening

• First-degree relatives of SPS patients should be offered colonoscopic screening at age 40 years or 10 years before the diagnosis of the index case 1
• First-degree relatives should have surveillance examinations every 5 years unless polyp burden indicates more frequent examination 1

Common Pitfalls

1. Inadequate clearing: Failure to completely remove all polyps >5 mm before starting surveillance
2. Insufficient quality of colonoscopy: Not using dye spray or high-definition endoscopy to detect subtle serrated lesions
3. Inappropriate extension of intervals: Extending intervals beyond 2 years even when polyps ≥10 mm are found
4. Missing dysplastic lesions: Failing to carefully examine for and remove sessile serrated adenomas with dysplasia, which have higher malignant potential

By following this surveillance protocol, the risk of CRC in SPS patients can be effectively managed through endoscopic control of polyp burden.