High-intensity surveillance after adenoma removal in colorectal cancer provides modest, clinically relevant benefits at an acceptable cost compared with low-intensity surveillance, according to study results published in Annals of Internal Medicine.

Early detection and removal of precancerous adenomas in colorectal cancer is shown to reduce the risk for death, but there are few outcome data on how to appropriately manage patients who have had adenomas removed. Current strategies require a substantial amount of resources, which has raised concerns that surveillance may not be cost-effective given that colonoscopy performance continues to improve and adenoma removal may defer additional testing for 10 years. The objective of this study was to compare the lifetime benefits and costs of high-intensity surveillance versus low-intensity surveillance.

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In this study, researchers assessed average-risk patients aged 50, 60, and 70 years who had low-risk adenomas (LRAs) or high-risk adenomas (HRAs) removed at screening with colonoscopy or fecal immunochemical testing. The model evaluated high-intensity surveillance strategies for patients at 5 years after LRA removal and 3 years after HRA removal, and low-intensity surveillance strategies for patients at 10 years after LRA removal and 5 years after HRA removal.

Surveillance was stopped when patients were diagnosed with colorectal cancer, turned 80 years of age, or died, whichever came first. The model also evaluated return to routine screening after 10 years with screening colonoscopy every 10 years or yearly fecal immunochemical testing, as well as no further surveillance or screening beyond baseline. Primary outcomes were lifetime colorectal cancer incidence and cost-effectiveness ratios. Other outcomes were costs and colonoscopy resources used.

Results revealed that without surveillance or further screening, the cumulative number of colorectal cancer cases in patients aged 50 years who had LRAs removed at screening colonoscopy would increase nonlinearly from 7 per 1000 patients after 10 years to 72 per 1000 patients after 30 years and to 109 per 1000 patients with lifetime follow-up. Returning to colonoscopy screening reduced the lifetime risk for colorectal cancer by 39%, low-intensity surveillance decreased the risk by 46%, and high-intensity surveillance decreased the risk by 55%, with proportionate reductions in CRC mortality. The lifetime colorectal cancer risk for patients aged 50 years with HRAs removed at screening colonoscopy was 172 cases per 1000 patients, which was 1.6 times higher than in patients with LRAs removed. 

For patients with LRAs removed, high- vs low-intensity surveillance had incremental cost-effectiveness less than $30,000 per quality-adjusted life-years (QALY) gained. For patients with HRAs removed, the cost-effectiveness ratio for high- vs low-intensity surveillance was less than $20,000 per QALY gained.

Results from sensitivity analyses revealed that all evaluated scenarios for patients aged 50 years resulted in incremental cost-effectiveness ratios that were less than $50,000 per QALY gained for low-intensity surveillance, compared with return to screening and high- vs low-intensity surveillance. Scenarios with cost-effectiveness ratios exceeding $50,000 per QALY gained were a 50% increase in colonoscopy cost, surveillance up to age 100 years vs 80 years, and near-perfect quality of colonoscopy.

The main limitation of this study was that there are no data available with a follow-up longer than 20 years; therefore, researchers remain uncertain about the development of colorectal cancer over time across individual patients. Furthermore, the study does not distinguish histologic features of adenomas or consider sessile serrated polyps separately. However, it is suggested that if adenoma surveillance also reduces CRC incidence in patients with serrated polyps, then timely surveillance may provide additional benefit for patients with synchronous serrated polyps.

The study researchers concluded that high-intensity surveillance after removal of adenoma provides modest incremental clinical benefits at an acceptable cost over return to routine screening or low-intensity surveillance and that current US recommendations for 5-year and 3-year surveillance following LRA removal and HRA removal, respectively, remain reasonable. Follow-up longer than 20 years will be required to appropriately assess the effect of high- versus low-intensity surveillance.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Meester RGS, Lansdorp-Vogelaar I, Winawer SJ, Zauber AG, Knudsen AB, Ladabaum U. High-intensity versus low-intensity surveillance for patients with colorectal adenomas: a cost-effectiveness analysis [published online September 24, 2019]. Ann Intern Med. doi: 10.7326/M18-3633