How long does it take until the effects of endoscopic screening on colorectal cancer mortality are fully disclosed?: a Markov model study

Abstract

A recent randomized trial has suggested persisting protection from colorectal cancer (CRC) incidence and mortality of a single flexible sigmoidoscopy for up to 17 years and possibly beyond. We performed a simulation study to explore the time course and magnitude of protection provided by screening colonoscopy against CRC death over 25 years. Using data from the German national screening colonoscopy registry, a multistate Markov model was set up based on the adenoma-carcinoma pathway to estimate cumulative CRC mortality when different proportions of the population have a single screening colonoscopy at age 55, or two screening colonoscopies at ages 55 and 65. Cumulative CRC mortality continuously increased with age and reached 2.6 and 1.7% at age 80 in the absence of screening for men and women, respectively. A single colonoscopy at age 55, even with limited uptake, would lead to much lower cumulative mortality (0.7% for men and 0.5% for women at age 80 under 100% uptake). Relative mortality reduction continued to increase over more than 10 years and reached the maximum around 12-13 years after screening. Absolute risk reduction steadily increased throughout follow-up and more than half of the total risk reduction would occur between 15-25 years. A repeat colonoscopy 10 years later further enhanced the effects and cumulative mortality remained at 0.1-0.2% under 100% uptake. Even a single (once-only) screening colonoscopy has the potential to prevent most of CRC mortalities. Protective effects are expected to be long-lasting and to become fully manifest after more than two decades from screening.

Changes in colorectal cancer screening use after introduction of alternative screening offer in Germany: Prospective cohort study

“…In summary, despite these limitations, our study suggests that introduction of screening colonoscopy as an alternative screening offer in Germany increased adherence to CRC screening overall, with screening colonoscopy becoming the primary source for being up-to-date with CRC screening after 5-6 years. These encouraging results, along with model-based projections, 31,32 suggest that major reduction of CRC incidence and mortality is to be expected in the years and decades to come, which has already started to become evident in recent years and which could potentially be further enhanced by switching to an organized CRC screening program.…”

Model based evaluation of long‐term efficacy of existing and alternative colorectal cancer screening offers: A case study for Germany

“…The model's natural history assumptions were derived step‐by‐step in several previous analyses using data from the German screening colonoscopy registry, the world's largest registry of its kind 15‐17 . CRC mortality rates were estimated using data from a German case‐control study and German registry data 18,19 . General mortality rates and average life expectancy were extracted from German population life tables 20 .…”

Age-specific sequence of colorectal cancer screening options in Germany: A model-based critical evaluation

“…We set up a multistate Markov model to simulate the natural history of CRC based on the adenoma-carcinoma process (Fig 1). Background information on the model's structure and data sources has been reported previously [10][11][12][13][14]. Briefly, simulation is performed on a hypothetical previously unscreened German population of 100,000 men and 100,000 women for a predefined number of years, whereby screening can interfere with the natural history of CRC.…”