Negative finding on high quality screening colonoscopy portends long term low risk

Results of an observational study by researchers in Poland suggested that it may be safe to extend the interval between colonoscopies to more than 10 years for adults who have a negative finding on a single high-quality screening colonoscopy.

That finding emerged from an analysis of 165,887 individuals included in a screening registry, reported Nastazja Dagny Pilonis, MD, of the Maria Sklodowska-Curie National Research Institute of Oncology and Medical Center for Postgraduate Education, Warsaw, Poland, and colleagues in Annals of Internal Medicine.

They analyzed data from a cohort of average risk adults ages 50 to 66 — a group that should be screened every 10 years, according to current recommendations.

“A single negative high-quality screening colonoscopy was associated with reduced CRC incidence and mortality for up to 17.4 years,” they wrote. “The reduction rates for the period beyond the currently recommended 10-year interval (10 to 17.4 years) did not significantly differ from those in the earlier observation periods. This was mainly driven by long-lasting reductions in CRC incidence and mortality (by 84% and 90%, respectively) after high-quality screening colonoscopies. High quality was key for the profound long-term efficacy of screening colonoscopy in the proximal colon, and among women. These findings are of paramount importance, because previous reports have questioned the efficacy of colonoscopy in the proximal colon and of screening sigmoidoscopy in women.”

During the more than 17-years of follow-up, the CRC incidence was 72% lower and mortality was 81% lower than the general population, which was used as comparator. “High-quality examination resulted in 2-fold lower CRC incidence (SIR, 0.16 [CI, 0.13-0.20]) and mortality (SMR, 0.10 [CI, 0.06 to 0.14]) than low-quality examination (SIR, 0.32 [CI, 0.29-0.35]; SMR, 0.22 [CI, 0.18-0.25]). In multivariable analysis, the hazard ratios for CRC incidence after high-quality versus low-quality colonoscopy were 0.55 (CI, 0.35-0.86) for 0 to 5 years, 0.54 (CI, 0.38-0.77) for 5.1 to 10 years, and 0.46 (CI, 0.25-0.86) for 10 to 17.4 years.”

Pilonis and colleagues said they believe their study is the first to “include baseline examination quality in the analysis of long-term risk for CRC and mortality after negative colonoscopy.”

They noted that “some proximal precursor lesions (for example, sessile serrated polyps) are very subtle and indistinct, such that endoscopists require specific knowledge to recognize and differentiate them from surrounding healthy mucosa. In our study cohort, we cannot prove that high-quality colonoscopy was associated with better detection of sessile serrated polyps, but other studies have shown that high [adenoma detection rate] is correlated with detection of sessile serrated polyps. Our results suggest that high quality colonoscopy provides long-lasting reductions in distal and proximal CRC incidence and mortality, but the magnitude of effect may still be lower for the proximal colon.”

The quality of the examination was particularly important for assessing CRC incidence and death in women. “After high-quality colonoscopy, the incidence and mortality reduction rates in women were similar to those in men and were stable across the entire follow-up,” they wrote. “After low-quality colonoscopy, incidence rates in women were significantly higher than the rates observed in men throughout the follow-up. This was also seen for mortality rates during 5.1 to 10 years after examination.”

They listed a number of limitations to the study, including the fact that aside from age and gender, it was not possible to adjust for differences between the study cohort and the general population cohort. Factors such as diet, exercise, and income were not assessed as potential confounders. “Furthermore, this comparison allowed quantification of the predictive but not protective effects of screening, because negative screening colonoscopy does not include therapeutic intervention; rather, it ascertains that an individual is free of neoplasia at that time,” they wrote.

“Second, the data on CRC diagnoses and deaths were derived from the National Cancer Registry, which is 90% complete. Registration completeness remained relatively stable over the follow-up, and it is assumed not to influence our study results,” they added.

They acknowledged that the follow-up time for persons with high quality colonoscopy was slightly shorter than those who had low quality colonoscopy, which they said was due to a “natural consequence of improving colonoscopy quality over the study inclusion period.”

A final limitation cited by the authors was that it is possible that some individuals actually had follow-up colonoscopies outside the Polish Registry Screening Program.

They concluded that the results not only support the safety of the current 10-year interval but also suggest that the interval could be extended, “provided that quality metrics are universally assessed and the baseline examination meets recommended standards.”

  1. Be aware that analyses of registry data suggest that, following a single negative finding from a high-quality screening colonoscopy, the risk of CRC or death remains low for more than 17 years.

  2. Note that the authors caution that a negative finding from a low-quality screening colonoscopy does not provide the same long-term assurance of low risk.

Peggy Peck, Editor-in-Chief, BreakingMED™

Pilonis reported support from the Polish Ministry of Health and the Medical Center for Postgraduate Education in Warsaw and the Polish Foundation of Gastroenterology.

Cat ID: 23

Topic ID: 78,23,730,16,23,935,142,925