Two recent studies used simulations to try to optimize screening strategies for colorectal cancer.
In the first study, researchers simulated a cohort of 10 million people of different ages and different family histories (from zero to four first-degree relatives with colorectal cancer). They considered screening strategies with an incremental cost-effectiveness ratio below $100,000 per quality-adjusted life-year to be cost effective. The simulation showed that screening every three years beginning at age 40 years was most cost-effective for people with one affected relative (which is true of 92% of people with a family history, according to the data used in the study). If no adenomas were found, the screening interval could be extended to five years at age 45 years and seven years at age 55 years, the simulation showed. For people with more affected relatives, screening should start at a younger age and be more frequent but could also be reduced if no abnormalities were found.
Screening on a three-year interval “may seem aggressive, and is more intensive than existing guidelines,” the study authors said. They suggested that “guidelines could be improved by a more detailed grouping of family history.” The authors noted a number of limitations, including that an individual's number of affected relatives is dependent on his or her family size and that the model they used was calibrated from cancer incidence data before the onset of screening. The study was published online by Gastroenterology on Sept. 27.
The other study, conducted in the Netherlands and published in the Oct. 17 Annals of Internal Medicine, analyzed the effectiveness of fecal immunochemical testing (FIT) with and without postpolypectomy surveillance colonoscopy by modeling screening of asymptomatic people with no prior colorectal cancer diagnosis ages 55 to 75 years. They found that biennial FIT screening with no surveillance reduced colorectal cancer mortality by 50.4% compared with no screening or surveillance. Adding surveillance according to Dutch guidelines (low-risk patients get FIT 10 years later, intermediate-risk patients get colonoscopy five years later, and high-risk patients get colonoscopy after three years) reduced mortality by an additional 1.7% but increased colonoscopies and therefore cost by €68,000 for a gain of 0.9 life-year. Extending the surveillance interval to five years decreased the colonoscopy cost without substantial loss of effectiveness, although it still did not meet the Dutch standard of cost-effectiveness, the study found.
The study authors noted that thresholds for determining cost-effectiveness differ among countries, so additional analyses would be required to make country-specific recommendations for surveillance. The study was also limited by its evaluation of only a few surveillance strategies. They noted that more information should be provided by a trial currently under way in which people are randomly assigned to a surveillance interval based on the findings in an initial colonoscopy.