Quantifying the impact of adherence to screening on colorectal cancer incidence and mortality

Abstract

Abstract Background Current recommendations of The US Preventive Services Task Force (USPSTF) on colorectal cancer (CRC) screening strategies are based on models that assume 100% adherence to screening. Since adherence can largely affect the outcomes of a screening modality, we aimed to assess the comparative effectiveness of CRC screening strategies under published rates of actual adherence. Methods We developed an individual-level simulation model and validated it against landmark trials and USPSTF models. Then we assessed the effectiveness of colonoscopy (COL), flexible sigmoidoscopy (FS), high-sensitivity guaiac fecal occult blood test (HS-gFOBT), fecal immunochemical test (FIT), multitarget stool DNA test (FIT-DNA), computed tomography colonography (CTC), and methylated SEPT9 DNA test (SEPT9) in reducing CRC incidence and mortality. For each strategy, we also estimated the incremental life-years gained, number of colonoscopies, and adverse events. Results Assuming 100% adherence, FIT-DNA, FIT, HS-gFOBT, and SEPT9 averted 58 to 59 CRC cases and 28 CRC deaths; COL and CTC strategies 56 cases and 27 deaths, while FS averted 39 cases and 19 deaths per 1,000 individuals. Life-years gained were similar across FIT-DNA, FIT, HS-gFOBT, SEPT9, CTC, and COL strategies. The total number of colonoscopies was highest with COL (3,567), followed by SEPT9 (3,231), HS-gFOBT (2,584), FIT-DNA (2,079), FIT (2,067), CTC (1,691) and FS (1,538) strategies. Assuming actual adherence, SEPT9 averted 54 CRC cases and 26 CRC deaths, followed by COL with 49 cases and 24 deaths, and FIT-DNA, FIT, CTC and HS-gFOBT with approximately 36 to 41 cases and 18 to 21 deaths averted per 1000 individuals screened. Life-years gained reflected the effectiveness of each strategy in reducing CRC cases and deaths. Conclusions Adherence is a key factor in determining the effectiveness of CRC screening and strategies with higher expected adherence rates have the potential to reduce cancer incidence and mortality. Key messages Adherence has a substantial impact on screening outcomes, such as cancer incidence and mortality, and may influence selection of optimal screening strategies. Strategies with higher expected adherence rates can lead to clinically meaningful benefits compared to strategies that may have better one-time sensitivity and/or specificity.