Individuals with polyps ≥10 mm without other high risk features have a similarly low post-colonoscopy colorectal cancer risk to those with no polyps

Background:

Current post-polypectomy guidelines recommend a 3-year surveillance colonoscopy for individuals with polyps =10 mm as the sole high risk feature, although the necessity of such strict surveillance, particularly for polyps of 10-20 mm, remains uncertain. We aimed to compare post-colonoscopy colorectal cancer (PCCRC) risk between these individuals and those without polyps at baseline colonoscopy. 

Methods:

Data of quality-assured baseline colonoscopies in the Dutch fecal immunochemical test (FIT)-based CRC screening program (2014-2020) were used. According to the guidelines prevailing at that time, a subset of individuals with =10-mm adenomas without high grade dysplasia or serrated polyps ≥10mm without dysplasia were advised 5-year surveillance. For these individuals, PCCRC risk within 5 years was assessed and compared with the risk of polypfree individuals using multilevel Cox regression analysis. 

Results:

Of all individuals with high risk polyps, 79% had polyps ≥10mm and 46% had polyps 10-20mm as the sole high risk feature. In total 21 522 individuals with ≥10-mm polyps and 69 688 individuals without polyps were included in comparative analyses. PCCRC incidence per 10 000 person-years of follow-up was 3.07 (95%CI 1.76-4.38) for individuals with ≥10-mm polyps and 5.02 (95%CI 4.08-5.97) for individuals without polyps. Risk of PCCRC was comparable between the two groups (hazard ratio 0.67, 95%CI 0.42-1.07).

Conclusions:

PCCRC risk 5 years after baseline colonoscopy for individuals with polyps ≥10mm without other high risk features is not significantly different from individuals without polyps at baseline. Lengthening surveillance intervals would affect 79% of high risk individuals with ≥10-mm polyps as their sole high risk feature, and 46% if limited to those with polyps of 10-20mm.