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Session: ePoster Monitor 3-Colon Cancer 12

eP714 - Adenoma Detection Rates for Lynch Syndrome Patients at First, Second and Third Colonoscopy Stratified by Type of Lynch Syndrome

Tuesday, June 4, 2024
7:48 AM – 7:53 AM ET, USA
Location: Baltimore Convention Center, Room 318-320

    ePoster Presenter(s)

  • Douglas Riegert-Johnson, MD

    Consultant of Clinical Genomics
    Mayo Clinic
    Mayo Clinic College of Medicine
    Jacksonville, FL, United States

    All of the relevant financial relationships listed below have been mitigated.
    This individual has no financial relationships with ineligible companies.

Purpose/Background: Lynch syndrome (LS) patients carry mutations in one of the DNA mismatch repair genes and are at high risk for colorectal cancer. In patients without LS, the colonoscopy adenoma detection rate (ADR) has been benchmarked as a quality measure for colorectal cancer prevention. Colonoscopy ADR benchmarks have not been validated for LS patients and little research has been reported on factors that affect LS patient ADRs. We report LS ADRs by LS gene the patient has a mutation in at first, second and third colonoscopy to assist in developing LS ADR benchmarks.Methods/Interventions: We reviewed the records of LS patients having colonoscopy. All patients had pathogenic or likely pathogenic variants (mutations) in one of the LS genes MSH2, MSH6, MLH1, and PMS2. High definition colonoscopes were used with a cecal intubation rate of 100%. Ninety five percent of patients had excellent bowel preparation (Boston Bowel Prep score = 9). Indigo carmine chromoendoscopy was used for all colonoscopies.Results/Outcomes: 112 LS patients had 490 colonoscopies with 351 years of follow up. The number of patients by LS gene with a mutation was MSH2 = 32, MSH6 = 29, MLH1 = 26 and PMS2 = 25. One patient was diagnosed with colorectal cancer at their initial index colonoscopy. No patient was diagnosed with colorectal cancer while under surveillance. The Table shows ADRs over time for first, second and third colonoscopies by LS gene with a mutation.Conclusion/

Discussion: Colorectal cancer is not common in LS patients having colonoscopy with the ADRs presented here. ADRs vary based on which LS gene mutation the patient has and also on whether the patient was having their first, second or third colonoscopy. The largest difference in ADRs was between MSH2 first colonoscopy (50%) and PMS2 third colonoscopy (20%). Several different LS ADRs will most likely need to be adopted based on these and other factors. Further validation with other datasets is needed before adopting colonoscopy ADR benchmarks for LS patients.