Among screening tests for colorectal cancer (CRC), the fecal immunochemical test (FIT) was found to be the most effective and cost-efficient intervention and Epi proColon® was found to be the most effective at expected real-world adherence rates, according to results from a microsimulation study reported in Gastrointestinal Endoscopy.
Investigators used the microsimulation-based colon modeling open-source tool (CMOST) to calculate the incidence reduction, mortality reduction, life years gained, and cost effectiveness of screening with the available screening modalities for CRC — colonoscopy, FIT, ColoGuard®, Epi proColon, and PolypDxTM — including various assumptions regarding screening adherence.
The researchers simulated 142,501 theoretical screening tests with variable assumptions for adenoma and carcinoma sensitivity, specificity, test frequency, and adherence, and identified highly efficient tests that outperformed colonoscopy. For available screening tests, they simulated 10 replicates of a virtual population of 2 million persons. Adherence to follow-up colonoscopy after a positive test was assumed to be 82%, and results of the theoretical tests were compared with CRC screening with colonoscopy at 100% adherence at ages 50, 60, and 70 years.
Among the theoretical tests, 6299 tests saved more life years than standard colonoscopy screening. Regarding the characteristics of efficient screening tests, all tests were associated with moderate adherence (at least ~50%).
Highly efficient theoretical screening tests were characterized by high sensitivity for advanced adenoma and carcinoma and high patient adherence. All simulated available screening tests were effective at 100% adherence to screening and at expected real-world adherence rates. In addition, all tests were considered cost-effective below the threshold of US $100,000 per life year gained. FIT was found to be the most effective and cost-efficient intervention, with perfect adherence, and Epi proColon was found to be the most effective at expected real-world adherence rates, according to the study authors.
“Our microsimulation study identified characteristics of highly efficient theoretical screening tests and confirmed effectiveness and cost-effectiveness of colonoscopy and available urine-, blood-, and stool-based tests,” stated the investigators. “Better patient adherence results in superior effectiveness for CRC prevention in the whole population.”
Yearly FIT and Epi proColon saved the highest number of life years when 100% adherence to screening was assumed. “Efficiency of all available screening modalities did not differ greatly, but their cost-effectiveness did,” noted the researchers. “Here, the cheap FIT performed best and was even cost-saving.”
A study limitation is the reliance on the literature for all variables, and so a recent increase in the incidence of CRC was not taken into account, and serrated polyps were not included in the analysis, the investigators noted.
“Our results point to the crucial importance of adherence to screening,” the study authors commented. “Thereby, incidence and mortality reduction by a test with a lower efficacy but better adherence and/or testing frequency can surpass effectiveness of colonoscopy in a population-based screening program.”
Deibel A, Deng L, Cheng C-Y, et al. Evaluating key characteristics of ideal colorectal cancer screening modalities: the microsimulation approach. Gastrointest Endosc. Published online February 15, 2021. doi:10.1016/j.gie.2021.02.013