Introduction
It is not clear whether the inverse relationship between colonoscopists’ adenoma detection rate (ADR) and post-colonoscopy colorectal cancer (PCCRC) is seamless or subject to “plateau” effect.
Aims & Methods
Aim of the study was to model the pattern of association between ADR and PCCRC. The present study is a systematic review and meta-analysis of studies published up to December 2024 providing the crude incidence rate of PCCRC according to various colonoscopists’ ADR categories. The primary outcome was calculated as the cumulative incidence of PCCRC at the lowest bound of each ADR category, starting from highest to lowest colonoscopists’ ADR. A restricted cubic spline multilevel metaregression analysis was applied to model the inverse association between ADR and cumulative PCCRC.
Results
After applying selection criteria, 7 studies published in 2020-2024, including 2,178,822 patients were included. All studies were conducted in organized CRC screening programs: 5 studies were set in primary colonoscopy screening, whereas 2 studies assessed FIT+ patients undergoing colonoscopy with two different cut-offs (20 µg Hgb/g and 47 µg Hgb/g feces). Four studies were European, and three studies were conducted in the US. Median patient age ranged from 57 to 65 years (see Table 1).
In primary colonoscopy setting (5 studies with 2,025,296 patients), adjusting for standardized follow-up and standardized CRC risk, cumulative incidence of CRC after colonoscopy showed a marked decrease for each 1-unit increase in ADR up to 27%, with a more gradual decline between 27% and 34%. In absolute numbers, assuming a 10-year follow-up period, CRC after colonoscopy ranged from 258/100,000 at 1% ADR, to 228/100,000 at 27% ADR, and 220/100,000 at 34% ADR, yielding a total decrease of 38 CRC after colonoscopy cases per 100,000 patients in 10 years. Beyond this threshold, according to model-based projections, CRC after colonoscopy would be 212/100,000 at 50% ADR, 207/100,000 at 60% ADR, and 197/100,000 at 80% ADR, yielding only an additional decrease of 8 (ADR 50%), 13 (ADR 60%), and 23 (ADR 80%) CRC after colonoscopy cases per 100,000 patients in 10 years, as compared to ADR 34%. Data remained consistent after excluding the study by Pilonis et al. [1], confirming that CRC after colonoscopy plateaus after 34% ADR. Heterogeneity was low (I2=0%) and the visual inspection of the funnel plot revealed some publication bias possibly leading to overestimate the inverse association between ADR and CRC after colonoscopy.
In the FIT-based setting (2 studies, 153,526 patients), quantitative synthesis was not performed owing to the low number of studies and different FIT thresholds (i.e., ≥20 and ≥47 µg Hb/g feces). Nonetheless, when examining the individual studies, there appears to be a more linear decline in post-colonoscopy CRC risk with increasing ADR.
Conclusion
In primary colonoscopy screening, achieving an ADR of at least 27% is essential. While increasing ADR beyond 27% continues to reduce risk, the benefit plateaus beyond ADR 34%, suggesting limited additional clinical advantage. Of note, the absolute risk reduction in CRC after colonoscopy is overall modest. Additional quality measures could provide a more comprehensive assessment of colonoscopy effectiveness.
References
Pilonis ND, Spychalski P, Kalager M, et al. Adenoma Detection Rates by Physicians and Subsequent Colorectal Cancer Risk. JAMA. Published Online First: 16 December 2024.
Wisse PHA, Erler NS, de Boer SY, et al. Adenoma Detection Rate and Risk for Interval Postcolonoscopy Colorectal Cancer in Fecal Immunochemical Test-Based Screening : A Population-Based Cohort Study. Ann Intern Med. 2022;175:1366–73.
Zorzi M, Antonelli G, Barbiellini Amidei C, et al. Adenoma Detection Rate and Colorectal Cancer Risk in Fecal Immunochemical Test Screening Programs : An Observational Cohort Study. Ann Intern Med. 2023;176:303–10.
Schottinger JE, Jensen CD, Ghai NR, et al. Association of Physician Adenoma Detection Rates With Postcolonoscopy Colorectal Cancer. JAMA. 2022;327:2114–22.
Waldmann E, Penz D, Šinkovec H, et al. Interval cancer after colonoscopy in the Austrian National Screening Programme: influence of physician and patient factors. Gut. 2021;70:1309–17.
Lam AY, Li Y, Gregory DL, et al. Association between improved adenoma detection rates and interval colorectal cancer rates after a quality improvement program. Gastrointest Endosc. 2020;92:355-364.e5.
Polychronidis G, He M-M, Vithayathil M, et al. Risk of colorectal neoplasia after removal of conventional adenomas and serrated polyps: a comprehensive evaluation of risk factors and surveillance use. Gut. 2024;73:1675–83.