Model supports high-intensity surveillance after detection of colorectal adenomas

The target population was U.S. patients ages 50, 60, or 70 years with low-risk or high-risk adenomas removed after screening via colonoscopy or fecal immunochemical testing.

A recently published model supported U.S. guidelines recommending surveillance colonoscopy every three years for patients with high-risk adenomas and suggested that a five-year surveillance interval may be reasonable in patients with low-risk adenomas.

To compare the lifetime benefits and costs of high- versus low-intensity surveillance, researchers conducted a microsimulation model of a U.S. cancer registry and used cost data from the published literature among U.S. patients ages 50, 60, or 70 years with low-risk adenomas (LRAs, one to two small adenomas) or high-risk adenomas (HRAs, three to 10 small adenomas or one or more large adenomas) removed after screening with colonoscopy or fecal immunochemical testing (FIT).

The model tested no further screening or surveillance, routine screening after 10 years, low-intensity surveillance 10 years after low-risk adenoma removal and five years after high-risk adenoma removal, and high-intensity surveillance five years after low-risk adenoma removal and three years after high-risk adenoma removal. The primary outcome measures were colorectal cancer incidence and incremental cost-effectiveness. Results were published Sept. 24 by Annals of Internal Medicine.

Without surveillance or screening, patients age 50 years had a lifetime colorectal cancer incidence of 10.9% after LRA removal and 17.2% after HRA removal at screening colonoscopy. Subsequent colonoscopic screening, low-intensity surveillance, and high-intensity surveillance decreased colorectal cancer incidence by 39%, 46% to 48%, and 55% to 56%, respectively. Colorectal cancer incidence and the benefits of surveillance were higher for adenomas detected by FIT and lower for older patients. High-intensity surveillance cost less than $30,000 per quality-adjusted life-year (QALY) gained versus low-intensity surveillance. In a sensitivity analysis, high-intensity surveillance cost less than $100,000 per QALY gained in most alternative scenarios for adenoma recurrence, colorectal cancer incidence, longevity, quality of life, screening ages, surveillance ages, test performance, disutilities, and cost.

The authors concluded that their study suggested modest incremental benefits with high-intensity surveillance after adenoma removal versus low-intensity surveillance or a return to routine screening. Their results support current U.S. recommendations for three-year surveillance after HRA removal and suggest that five-year surveillance after LRA removal is reasonable, they wrote. “Less intensive strategies may be preferred in different health care settings, depending on acceptable cost levels, available medical resources, and patient preferences,” the authors said. They called for future trials to validate their model's predications but noted that follow-up longer than 20 years may be required.

An accompanying editorial noted that the study results depend on the quality of the model inputs, that surveillance in clinical practice is “applied erratically,” and that retrospective studies that estimate benefit are imprecise.

“There is burgeoning identification of patients with preneoplastic colonic polyps but considerable uncertainty about the need for and timing of follow-up surveillance,” the editorialists wrote. “Going forward, we must seek answers to disease management with the same gusto we apply to disease discovery.”