A large population-based study of a colorectal cancer (CRC) screening program has shown that short-term risk of post-colonoscopy colorectal cancer (PCCRC) depends more on endoscopist performance than on the presence of high-risk polyps.
Researchers followed more than 239,000 individuals between 2014 and 2020 after a positive Dutch Fecal Immunochemical Test. Investigators compared whether cancers appearing within three years were linked more closely to polyp features or to the quality indicators of the endoscopist.
High-risk polyps—defined as adenomas 10 mm or larger, those with high-grade dysplasia, or multiple adenomas—are usually considered the main reason for shortened surveillance intervals. However, the study found no association between the presence of these polyps and the development of post-colonoscopy colorectal cancer within three years.
By contrast, endoscopist performance, as measured by adenoma detection rate (ADR) and proximal serrated polyp detection rate (PSPDR), showed strong inverse associations with risk. Each one-point increase in ADR was linked to a 6% reduction in post-colonoscopy cancer risk, and each one-point increase in PSPDR corresponded to an 8% reduction.
Individuals with no or low-risk polyps examined by an endoscopist with a high ADR had the lowest incidence of post-colonoscopy colorectal cancer, whereas those with high-risk polyps examined by endoscopists with low ADRs had the highest incidence. “The risk to develop PCCRC was at least two times higher in individuals with no or low-risk polyps examined by an endoscopist with low ADR or PSPDR compared with individuals with high-risk polyps but examined by an endoscopist with a high ADR or PSPDR,” wrote Nanette S. van Roermund, PhD, (Department of Gastroenterology and Hepatology, Amsterdam University Medical Center) and colleagues.
Similar patterns were observed when stratified by PSPDR. The researchers noted that incorporating ADR and PSPDR into risk stratification, or embedding them more firmly into quality assurance programs, could reduce the number of missed cancers. They also suggested that existing benchmarks may be set too low, noting that even though Dutch guidelines require an ADR of at least 40%, endoscopists in the lowest-performing category of this study had ADRs well above that threshold, yet still exhibited higher rates of missed cancers.
The study had some limitations. It focused on cancers occurring within three years of colonoscopy, a period when endoscopist quality appears to be most relevant, but longer-term risk may be more strongly influenced by polyp biology. The high baseline ADRs and PSPDRs in the Dutch program may also limit generalizability to settings with lower detection rates. In addition, by design, the study excluded individuals referred for more advanced endoscopic resection techniques, which may have influenced the risk profile of the high-risk polyp group.
“Nevertheless, [the study’s] timeframe also presents a major strength,” the authors added. “Previous long-term studies evaluating endoscopist performance in relation to polyp features are biased by the potential for increased surveillance in individuals with high-risk polyp, making their results challenging to interpret.”
Strengthening national quality assurance programs, raising minimum benchmarks, and providing training to improve detection rates could help reduce the burden of post-colonoscopy colorectal cancer, noted researchers.
Conflicts of interest are available in the link below.
Source: Clinical Gastroenterology & Hepatology
