Estimating the impact of differential adherence on the comparative effectiveness of stool-based colorectal cancer screening using the CRC-AIM microsimulation model

Estimated impact and value of blood-based colorectal cancer screening at varied adherence compared with stool-based screening

OBJECTIVE

This analysis estimated the outcomes of triennial blood-based colorectal cancer (CRC) screening at various adherence, including perfect adherence, compared with triennial multi-target stool DNA (mt-sDNA) screening at the reported real-world adherence rate.

METHODS

The validated CRC-AIM model simulated a US cohort of average-risk individuals receiving triennial screening with mt-sDNA or blood-based test from ages 45 to 75 years. Modeled specificity and sensitivity were based on reported data. Adherence was set at a real-world rate of 65.6% for mt-sDNA and at 65.6%, relative 10% incremental increases from 65.6%, or 100% for the blood-based test. Costs of mt-sDNA and the blood-based test were based on prices for clinically available tests ($508.87 and $895, respectively). Value-based pricing was estimated at a willingness-to-pay threshold of $100,000.

RESULTS

Both tests resulted in life-years gained (LYG), reduced CRC cases, and reduced deaths versus no screening. With adherence for mt-sDNA set at 65.6% and for blood-based test set at 100%, mt-sDNA resulted in 30% more LYG, 52% more averted CRC cases, and 32% more averted CRC deaths. At reported sensitivity and specificity rates, mt-sDNA at 65.6% adherence dominates (is more effective and less costly) the blood-based test at any adherence. There was no price at which triennial screening with the blood-based test at any adherence was cost-effective compared with mt-sDNA at 65.6% adherence.

CONCLUSIONS

Triennial screening with mt-sDNA resulted in better clinical outcomes at a lower cost compared with the modeled blood-based test even at perfect adherence, supporting application of blood-based tests only as a secondary screening option.

Impact of Eliminating Cost-Sharing by Medicare Beneficiaries for Follow-Up Colonoscopy After a Positive Stool-based Colorectal Cancer Screening Test

Medicare coverage of a follow-up colonoscopy after a positive stool-based colorectal cancer screening test with no patient cost-sharing started January 2, 2023, which may favorably affect screening behavior. This analysis estimated the clinical and economic effects of increased colorectal cancer screening participation potentially resulting from this policy change in Medicare beneficiaries. The validated Colorectal Cancer and Adenoma Incidence & Mortality (CRC-AIM) model simulated three guideline-endorsed colorectal cancer screening strategies for average-risk individuals (colonoscopy every 10 years, annual fecal immunochemical test, triennial multitarget stool DNA) from ages 65-75 years. The base-case scenario assumed 0% coinsurance for initial screening and follow-up colonoscopy, real-world screening test use (colonoscopy = 45.3%, stool-based test = 24.4%, unscreened = 30.3%), and real-world follow-up colonoscopy rates. Comparative scenarios assumed an increase in the overall screening rate from 0% to 15% (5% increments) and an increase in the follow-up colonoscopy rate from 0% to 15% (5% increments). The base-case scenario resulted in 128 life-years gained (LYG)/1,000 individuals versus no screening and total screening and treatment costs of $7,938/person. The changes resulted in an increase of up to 26 LYG/1,000 individuals and a decrease in total screening and treatment costs by as much as $128/person. Follow-up colonoscopy at $0 coinsurance became cost-saving with any increase in either overall screening or follow-up colonoscopy. Policies that remove cost barriers to completing colorectal cancer screening may increase rates of screening participation, potentially improving economic and clinical outcomes.

SIGNIFICANCE

A follow-up colonoscopy after a positive stool-based colorectal cancer screening test is necessary to complete the full screening process. Policies that remove cost barriers to completing colorectal cancer screening may lead to increases in overall participation rates and use of follow-up colonoscopy, improving clinical and economic outcomes.

Multitarget Stool DNA Testing Has High Positive Predictive Value for Colorectal Neoplasia on the Second Round of Testing

BACKGROUND & AIMS

Multitarget stool DNA (mt-sDNA) testing is a stool-based screening test for colorectal cancer (CRC). In a single instance of testing, the pivotal Food and Drug Administration-approval study (NCT01397747) found that 16% of mt-sDNA tests were positive, and the positive predictive value (PPV) for CRC or advanced precursor lesions (APL) was 27.3%. We aimed to examine real-world longitudinal performance by determining the test-positive rate and PPV of mt-sDNA on the second round of testing.

METHODS

Colonoscopy and pathology reports were reviewed retrospectively for patients with a negative mt-sDNA on the first round of screening and a positive mt-sDNA on the second round. The test-positivity rate and PPV for CRC, APL, and any colorectal neoplasia were calculated for the second mt-sDNA and compared with baseline PPVs from a previously published cohort of patients from our institution who tested positive on the first round of screening.

RESULTS

A total of 2758 patients completed a second test at a median of 3.2 years after the first test. Of these, 422 (15%) had a positive second mt-sDNA. The PPV was 0.25% for CRC, 24% for APL, and 67% for any colorectal neoplasia. There was no significant difference in PPV on the second mt-sDNA test compared with the first round (24% vs 28% for APL; P = .12).

CONCLUSIONS

mt-sDNA test positive rate and PPV were similar between the first and second rounds of screening. These observations confirm the utility of a second round of mt-sDNA screening and may inform estimates of mt-sDNA effectiveness for CRC screening.

Comparison of Simulated Outcomes Between Stool- and Blood-Based Colorectal Cancer Screening Tests

The Centers for Medicare & Medicaid Services (CMS) recommend covering blood-based tests meeting proposed minimum performance thresholds for colorectal cancer (CRC) screening. Outcomes were compared between currently available stool-based screening tests and a hypothetical blood-based test meeting CMS minimum thresholds. Using the Colorectal Cancer and Adenoma Incidence and Mortality Microsimulation Model (CRC-AIM), outcomes were simulated for average-risk individuals screened between ages 45 and 75 years with triennial multitarget stool DNA (mt-sDNA), annual fecal immunochemical test (FIT), and annual fecal occult blood test (FOBT). Per CMS guidance, blood-based CRC screening was modeled triennially, with 74% CRC sensitivity and 90% specificity. Although not specified by CMS, adenoma sensitivity was set between 10% and 20%. Published adenoma and CRC sensitivity and specificity were used for stool-based tests. Adherence was set at (1) 100%, (2) 30%-70%, in 10% increments, and (3) real-world rates for stool-based tests (mt-sDNA = 65.6%; FIT = 42.6%; FOBT = 34.4%). Assuming perfect adherence, a blood-based test produced ≥19 lower life-years gained (LYG) than stool-based strategies. At the best-case scenario for blood-based tests (100% adherence and 20% adenoma sensitivity), mt-sDNA at real-world adherence achieved more LYG (287.2 vs. 297.1, respectively) with 14% fewer colonoscopies. At 100% blood-based test adherence and real-world mt-sDNA and FIT adherence, the blood-based test would require advanced adenoma sensitivity of 30% to reach the LYG of mt-sDNA (297.1) and ∼15% sensitivity to reach the LYG of FIT (258.9). This model suggests that blood-based tests with CMS minimally acceptable CRC sensitivity and low advanced adenoma sensitivity will frequently yield inferior outcomes to stool-based testing across a wide range of adherence assumptions.

Inappropriate Multi-Target Stool DNA Use for Colorectal Cancer Screening: Risks, Compliance, and Outcomes

Background Inappropriate or "off-label" use of multi-target stool DNA (mt-sDNA) tests refers to their use in patients for whom colonoscopy or no testing at all is warranted. Examples include a positive family history of colorectal cancer, a history of inflammatory bowel disease, or medical issues necessitating diagnostic colonoscopy, among others. Current understanding of off-label mt-sDNA use for colorectal cancer screening, its associated risks, and outcomes is lacking. We examined off-label mt-sDNA prescription and compliance with testing in an outpatient setting in southeast Michigan. Aims The primary aims of the study were determining the extent of off-label mt-sDNA testing and compliance, and results of all testing, as well as demographic factors associated with off-label prescriptions. The secondary aims were to examine explanations for incomplete testing and factors contributing to successful completion. Methods Using a retrospective design, we identified mt-sDNA orders from outpatient internal medicine clinics between January 1, 2018, to July 31, 2019, to evaluate the proportion of off-label mt-sDNA, results of testing, and follow-up colonoscopies up to one year after order placement. Patients were categorized as "off-label" if any inappropriate criteria were met. Statistical analysis was performed for primary and secondary outcomes. Results From 679 mt-sDNA orders within the study period, 81 (12.1%) had at least one off-label criterion for testing. In total, 404/679 (59.5%) patients completed testing. Lack of follow-up comprised the majority of incompletions (216/275; 78.6%). Only 52 (70.3%) out of 74 positive results were followed by diagnostic colonoscopy. Retired employment status (OR = 1.87; 95%CI, 1.17-2.98; P = 0.008) and age of 76 years or older (OR = 2.28; 95%CI, 0.99-5.21; P = 0.044) were significantly associated with increased risk of off-label mt-sDNA prescription. Increasing age range was associated with higher test completion (χ2 (5) = 12.085, p = 0.034). Multinomial logistic regression revealed an increasing age range (OR = 1.29; 95% CI, 1.09-1.54; P = 0.004), predictive of a positive mt-sDNA result for both groups. There was no significant difference between off-label or on-label groups in the mean number of resected polyps or pathology scores on follow-up colonoscopy. Conclusions Off-label mt-sDNA use remains a concern in the outpatient setting. Compliance for test completion and follow-up colonoscopy for positive results require further improvement. Our findings shed new light on the factors associated with off-label testing while reiterating its burden. We also describe common reasons for incomplete tests in an attempt to augment future colorectal cancer (CRC) screening initiatives.

Colorectal cancer statistics, 2023

Colorectal cancer (CRC) is the second most common cause of cancer death in the United States. Every 3 years, the American Cancer Society provides an update of CRC statistics based on incidence from population-based cancer registries and mortality from the National Center for Health Statistics. In 2023, approximately 153,020 individuals will be diagnosed with CRC and 52,550 will die from the disease, including 19,550 cases and 3750 deaths in individuals younger than 50 years. The decline in CRC incidence slowed from 3%-4% annually during the 2000s to 1% annually during 2011-2019, driven partly by an increase in individuals younger than 55 years of 1%-2% annually since the mid-1990s. Consequently, the proportion of cases among those younger than 55 years increased from 11% in 1995 to 20% in 2019. Incidence since circa 2010 increased in those younger than 65 years for regional-stage disease by about 2%-3% annually and for distant-stage disease by 0.5%-3% annually, reversing the overall shift to earlier stage diagnosis that occurred during 1995 through 2005. For example, 60% of all new cases were advanced in 2019 versus 52% in the mid-2000s and 57% in 1995, before widespread screening. There is also a shift to left-sided tumors, with the proportion of rectal cancer increasing from 27% in 1995 to 31% in 2019. CRC mortality declined by 2% annually from 2011-2020 overall but increased by 0.5%-3% annually in individuals younger than 50 years and in Native Americans younger than 65 years. In summary, despite continued overall declines, CRC is rapidly shifting to diagnosis at a younger age, at a more advanced stage, and in the left colon/rectum. Progress against CRC could be accelerated by uncovering the etiology of rising incidence in generations born since 1950 and increasing access to high-quality screening and treatment among all populations, especially Native Americans.

The cost-effectiveness of non-invasive stool-based colorectal cancer screening offerings from age 45 for a commercial and medicare population

AIM

The United States Preventive Services Taskforce (USPSTF) recently recommended lowering the age for average-risk colorectal cancer (CRC) screening from 50 to 45 years. While initiating screening at age 45 versus 50 provides a greater opportunity for CRC early detection and prevention, the full profile of benefits, risks, and cost-effectiveness of expanding the screen-eligible population requires further evaluation.

MATERIALS AND METHODS

The costs and clinical outcomes for screening at age 45 for triennial multi-target stool DNA [mt-sDNA], and other non-invasive stool-based modalities (annual fecal immunochemical test [FIT] and annual fecal-occult blood test [FOBT]), were estimated using the validated CRC-AIM microsimulation model over a lifetime horizon. Test sensitivity and specificity inputs were based on 2021 USPSTF modeling analyses; adherence rates were based on published real-world data and the costs of the screening test, follow-up colonoscopies, complications, and CRC care were included. Outcomes are reported from the perspective of a United States payer as clinical, life-years gained (LYG), and incremental cost-effectiveness ratio (ICER); stool-based and follow-up colonoscopy adherence ranges were explored in one-way, probabilistic and threshold analyses.

RESULTS

When compared to initiation of CRC screening at age 45 versus 50, all modalities reduced both the incidence of and mortality from CRC and increased LYG. Initiating CRC screening at age 45 was cost-effective with an ICER of $59,816 and $35,857 per quality-adjusted life year (QALY) for mt-sDNA versus FIT and FOBT, respectively. In the threshold analyses, at equivalent rates to stool-based screening, mt-sDNA was always cost-effective at a willingness-to-pay threshold of $100,000 per QALY versus FIT and FOBT.

CONCLUSIONS

Initiating average-risk CRC screening at age 45 instead of age 50 increases the estimated clinical benefit by reducing disease burden while remaining cost-effective. Among stool-based screening modalities, mt-sDNA provides the most clinical benefit in a Commercial and Medicare population.

Impact of race-specific screening guideline on the uptake of colorectal cancer screening among young African Americans

BACKGROUND

African Americans (AAs) have had lower colorectal cancer (CRC) screening rates, higher incidence rate, and earlier mean age at onset. The 2017 U.S. Multi-Society Task Force (MSTF) recommended initiating CRC screening at age 45 for AAs and age 50 for non-AAs.

OBJECTIVE

To investigate the impact of the 2017 MSTF's race-specific guidelines on CRC screening rate among young AAs.

DESIGN, SETTING, AND PARTICIPANTS

We used the 2015 and 2018 National Health Interview Survey to provide nationally representative estimates. The study sample included adults aged between 45 and 75 without a history of CRC, excluding screening recipients for diagnosis or surveillance purposes.

MAIN MEASURES

The outcome is a binary variable of CRC screening. Primary independent variables were age and race category (non-AAs aged 45-49, AAs 45-49, non-AAs 50-75, AAs 50-75), a binary variable indicating before or after the 2017 MSTF guideline (2015 vs. 2018), and their interaction terms. We employed a multivariable logistic model, adjusting for individual characteristics, and accounting for complex survey design.

KEY RESULTS

Among the total sample (n = 21,735), CRC screening rate increased from 54.6% in 2015 to 58.5% in 2018 (p < 0.01). By age and race, the screening rate exhibited an increase for all age and race groups except for young non-AAs. Compared to young non-AAs, the adjusted predicted probability (APP) of screening for young AAs was significantly higher by 0.10 (average marginal effect, 0.10; 95% confidence interval, 0.01-0.19) in 2018, while the difference was insignificant in 2015. Racial differences in screening among older adults were not significant in both years. The CRC screening rate was substantially lower among young AAs compared to older AAs (17.2% vs. 65.5% in 2018).

CONCLUSION

The race-specific recommendation is an effective policy tool to increase screening uptake and would contribute to reducing cancer disparities among racial/ethnic minorities.

Cost-Effectiveness of Waiving Coinsurance for Follow-Up Colonoscopy after a Positive Stool-Based Colorectal Screening Test in a Medicare Population

Commercial insurance covers a follow-up colonoscopy after a positive colorectal cancer-screening test with no patient cost-sharing. Instituting a similar policy for Medicare beneficiaries may increase screening adherence and improve outcomes. The cost-effectiveness of stool-based colorectal cancer screening was compared across adherence scenarios that assumed Medicare coinsurance status quo (20% for follow-up colonoscopy) or waived coinsurance. The CRC-AIM model simulated previously unscreened eligible Medicare beneficiaries undergoing stool-based colorectal cancer screening at age 65 for 10 years. Medicare costs, colorectal cancer cases, colorectal cancer-related deaths, life-years gained (LYG), and quality-adjusted life-years (QALY) were estimated versus no screening. Scenario 1 (S1) assumed 20% coinsurance for follow-up colonoscopy. Scenario 2 (S2) assumed waived coinsurance without adherence changes. Scenarios 3-7 (S3-S7) assumed that waiving coinsurance increased real-world stool-based screening and/or follow-up colonoscopy adherence by 5% or 10%. Sensitivity analyses assumed 1%-4% increased adherence. Cost-effectiveness threshold was ≤$100,000/QALY. Waiving coinsurance without adherence changes (S2) did not affect outcomes versus S1. S3-S7 versus S1 over 10 years estimated up to 3.6 fewer colorectal cancer cases/1,000 individuals, up to 2.1 fewer colorectal cancer deaths, up to 20.7 more LYG, and had comparable total costs per-patient (≤$6,478 vs. $6,449, respectively) as reduced colorectal cancer medical costs offset increased screening and colonoscopy costs. In sensitivity analyses, any increase in adherence after waiving coinsurance was cost-effective and increased LYG. In simulated Medicare beneficiaries, waiving coinsurance for follow-up colonoscopy after a positive stool-based test improved outcomes and was cost-effective when assumed to modestly increase colorectal cancer screening and/or follow-up colonoscopy adherence.

PREVENTION RELEVANCE

Follow-up colonoscopy after a positive stool-based test is necessary to complete the colorectal cancer-screening process. This analysis demonstrated that in a simulated Medicare population, waiving coinsurance for a follow-up colonoscopy improved estimated outcomes and was cost-effective when it was assumed that waiving the coinsurance modestly increased screening adherence. See related Spotlight, p. 641.

Start of an era: circulating cell-free DNA for early detection of cancers

Effective screening modalities are currently available for only a small subset of cancers, and they generally have suboptimal performance with complicated procedures. Therefore, there is an urgent need to develop simple, accurate, and non-invasive methods for early detection of cancers. Genetic and epigenetic alterations in plasma circulating cell-free DNA (cfDNA) have shown the potential to revolutionize methods of early detection of cancers and facilitate subsequent diagnosis to improve survival of patients. The medical interest in cfDNA assays has been inspired by emerging single- and multi-early detection of cancers studies. This review summarizes current technological and clinical advances, in the hopes of providing insights into the development and applications of cfDNA assays in various cancers and clinical scenarios. The key phases of clinical development of biomarkers are highlighted, and the future developments of cfDNA-based liquid biopsies in early detection of cancers are outlined. It is hoped that this study can boost the potential integration of cfDNA-based early detection of cancers into the current clinical workflow.

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Liquid biopsy, characterized by minimal invasiveness and user friendliness, can identify multiple cancers at the early stage and localize the tissue of origin

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The state-of-the-art technology facilitates the application of circulating cell-free DNA (cfDNA) assays in the early detection of cancers

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cfDNA assays are expected to be integrated into the clinical workflow after technological refinement and clinical trial validation

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The development and application strategies of cfDNA assays in various cancers and clinical scenarios can vary, and the harm-and-benefit should be balanced carefully

Life-years gained resulting from screening colonoscopy compared with follow-up colonoscopy after a positive stool-based colorectal screening test

Screening colonoscopies for colorectal cancer (CRC) are typically covered without patient cost-sharing, whereas follow-up colonoscopies for positive stool-based screening tests often incur patient costs. The objective of this analysis was to estimate and compare the life-years gained (LYG) per average-risk screening colonoscopy and follow-up colonoscopy after a positive stool-based test to better inform CRC coverage policy and reimbursement decisions. CRC outcomes from screening and follow-up colonoscopies versus no screening were estimated using CRC-AIM in a simulated population of average-risk individuals screened between ages 45-75 years. The LYG/colonoscopy per 1000 individuals was 0.09 for screening colonoscopy and 0.29 for follow-up colonoscopy. 0.01 and 0.04 CRC cases and 0.01 and 0.02 CRC deaths were averted per screening and follow-up colonoscopies, respectively. Coverage policies should be revised to encourage individuals to complete recommended screening processes.

Optimal Strategies for Colorectal Cancer Screening

Colorectal cancer (CRC) imposes significant morbidity and mortality, yet it is also largely preventable with evidence-based screening strategies. In May 2021, the US Preventive Services Task Force updated guidance, recommending screening begin at age 45 for average-risk individuals to reduce CRC incidence and mortality in the United States (US). The Task Force recommends screening with one of several screening strategies: high-sensitivity guaiac fecal occult blood test (HSgFOBT), fecal immunochemical test (FIT), multi-target stool DNA (mt-sDNA) test, computed tomographic (CT) colonography (virtual colonoscopy), flexible sigmoidoscopy, flexible sigmoidoscopy with FIT, or traditional colonoscopy. In addition to these recommended options, there are several emerging and novel CRC screening modalities that are not yet approved for first-line screening in average-risk individuals. These include blood-based screening or “liquid biopsy,” colon capsule endoscopy, urinary metabolomics, and stool-based microbiome testing for the detection of colorectal polyps and/or CRC. In order to maximize CRC screening uptake in the US, patients and providers should engage in informed decision-making about the benefits and limitations of recommended screening options to determine the most appropriate screening test. Factors to consider include the invasiveness of the test, test performance, screening interval, accessibility, and cost. In addition, health systems should have a programmatic approach to CRC screening, which may include evidence-based strategies such as patient education, provider education, mailed screening outreach, and/or patient navigation, to maximize screening participation.

Lowering the colorectal cancer screening age improves predicted outcomes in a microsimulation model

AIMS

While most guidelines still recommend colorectal cancer (CRC) screening initiation at age 50 years in average-risk individuals, guideline-creating bodies are starting to lower the recommended age of initiation to 45 years to mitigate the trend of increasing CRC rates in younger populations. Using CRC-AIM, we modeled the impact of lowering the CRC screening initiation age, incorporating theoretical and reported adherence rates, for triennial multi-target stool DNA (mt-sDNA) or annual fecal immunochemical test (FIT) screening.

METHODS AND MATERIALS

Screening strategies were simulated for individuals without CRC at age 40 and screened from ages 50 to 75 or 45 to 75 years. Outcomes included CRC incidence, CRC mortality, and life-years gained (LYG) per 1000 individuals screened (compared with no screening). Models used theoretically perfect (100%) and previously reported (71% mt-sDNA; 43% FIT) adherence rates.

RESULTS

With perfect adherence, mt-sDNA and FIT resulted in 22.2 and 23.4 more predicted LYG, respectively, with screening initiation at age 45 versus 50 years; reported adherence resulted in 23.9 and 24.4 more LYG, respectively. With perfect adherence, screening initiation at age 45 versus 50 years resulted in 26.1 and 28.6 CRC cases, respectively, with mt-sDNA and 22.8 and 25.5 cases with FIT; with reported real-world adherence there were 28.5 and 31.2 cases, respectively, with mt-sDNA and 37.1 and 40.2 cases with FIT. Similar patterns were observed for CRC deaths. With screening initiation at age 45 and reported adherence, mt-sDNA averted 8.6 more CRC cases and 3.3 more deaths per 1000 individuals than FIT.

CONCLUSIONS

Estimated CRC screening outcomes improved by lowering the initiation age from 50 to 45 years. Incorporating reported adherence rates yields greater benefits from triennial mt-sDNA versus annual FIT screening.

Impact of Patient Adherence to Stool-Based Colorectal Cancer Screening and Colonoscopy Following a Positive Test on Clinical Outcomes

Colorectal cancer-screening models commonly assume 100% adherence, which is inconsistent with real-world experience. The influence of adherence to initial stool-based screening [fecal immunochemical test (FIT), multitarget stool DNA (mt-sDNA)] and follow-up colonoscopy (after a positive stool test) on colorectal cancer outcomes was modeled using the Colorectal Cancer and Adenoma Incidence and Mortality Microsimulation Model. Average-risk individuals without diagnosed colorectal cancer at age 40 undergoing annual FIT or triennial mt-sDNA screening from ages 50 to 75 were simulated. Primary analyses incorporated published mt-sDNA (71%) or FIT (43%) screening adherence, with follow-up colonoscopy adherence ranging from 40% to 100%. Secondary analyses simulated 100% adherence for stool-based screening and colonoscopy follow-up (S1), published adherence for stool-based screening with 100% adherence to colonoscopy follow-up (S2), and published adherence for both stool-based screening and colonoscopy follow-up after positive mt-sDNA (73%) or FIT (47%; S3). Outcomes were life-years gained (LYG) and colorectal cancer incidence and mortality reductions (per 1,000 individuals) versus no screening. Adherence to colonoscopy follow-up after FIT had to be 4%-13% higher than mt-sDNA to reach equivalent LYG. The theoretical S1 favored FIT versus mt-sDNA (LYG 316 vs. 297; colorectal cancer incidence reduction 68% vs. 64%; colorectal cancer mortality reduction 76% vs. 72%). The more realistic S2 and S3 favored mt-sDNA versus FIT (S2: LYG 284 vs. 245, colorectal cancer incidence reduction 61% vs. 50%, colorectal cancer mortality reduction 69% vs. 59%; S3: LYG 203 vs. 113, colorectal cancer incidence reduction 43% vs. 23%, colorectal cancer mortality reduction 49% vs. 27%, respectively). Incorporating realistic adherence rates for colorectal cancer screening influences modeled outcomes and should be considered when assessing comparative effectiveness. PREVENTION RELEVANCE: Adherence rates for initial colorectal cancer screening by FIT or mt-sDNA and for colonoscopy follow-up of a positive initial test influence the comparative effectiveness of these screening strategies. Using adherence rates based on published data for stool-based testing and colonoscopy follow-up yielded superior outcomes with an mt-sDNA versus FIT-screening strategy.

Cross-sectional adherence with the multi-target stool DNA test for colorectal cancer screening in a large, nationally insured cohort

PURPOSE

Colorectal cancer (CRC) is the second most deadly cancer in the USA. Early detection can improve CRC outcomes, but recent national screening rates (62%) remain below the 80% goal set by the National Colorectal Cancer Roundtable. Multiple options are endorsed for average-risk CRC screening, including the multi-target stool DNA (mt-sDNA) test. We evaluated cross-sectional mt-sDNA test completion in a population of commercially and Medicare-insured patients.

METHODS

Participants included individuals ages 50 years and older with commercial insurance or Medicare, with a valid mt-sDNA test shipped by Exact Sciences Laboratories LLC between January 1, 2018, and December 31, 2018 (n = 1,420,460). In 2020, we analyzed cross-sectional adherence, as the percent of successfully completed tests within 365 days of shipment date.

RESULTS

Overall cross-sectional adherence was 66.8%. Adherence was 72.1% in participants with Traditional Medicare, 69.1% in participants with Medicare Advantage, and 61.9% in participants with commercial insurance. Adherence increased with age: 60.8% for ages 50-64, 71.3% for ages 65-75, and 74.7% for ages 76 + years. Participants with mt-sDNA tests ordered by gastroenterologists had a higher adherence rate (78.3%) than those with orders by primary care clinicians (67.2%). Geographically, adherence rates were highest among highly rural patients (70.8%) and ordering providers in the Pacific region (71.4%).

CONCLUSIONS

Data from this large, national sample of insured patients demonstrate high cross-sectional adherence with the mt-sDNA test, supporting its role as an accepted, noninvasive option for average-risk CRC screening. Attributes of mt-sDNA screening, including home-based convenience and accompanying navigation support, likely contributed to high completion rates.

Real-world cost-effectiveness of stool-based colorectal cancer screening in a Medicare population

AIM

Multiple screening strategies are guideline-endorsed for average-risk colorectal cancer (CRC). The impact of real-world adherence rates on the cost-effectiveness of non-invasive stool-based CRC screening strategies remains undefined.

METHODS

This cost-effectiveness analysis from the perspective of Medicare as a primary payer used the Colorectal Cancer and Adenoma Incidence and Mortality Microsimulation Model (CRC-AIM) to estimate cost and clinical outcomes for triennial multi-target stool DNA (mt-sDNA), annual fecal immunochemical test (FIT) and annual fecal occult blood test (FOBT) screening strategies in a simulated cohort of US adults aged 65 years, who were assumed to either be previously unscreened or initiating screening upon entry to Medicare. Reported real-world adherence rates for initial stool-based screening and colonoscopy follow up (after a positive stool test result) were defined as 71.1% and 73.0% for mt-sDNA, 42.6% and 47.0% for FIT, and 33.4% and 47.0% for FOBT, respectively. The incremental cost-effectiveness ratio using quality-adjusted life years (QALY) was defined as the primary outcome of interest; other cost and clinical outcomes were also reported in secondary analyses. Multiple sensitivity and scenario analyses were conducted.

RESULTS

When reported real-world adherence rates were included only for initial stool-based screening, mt-sDNA was cost-effective versus FIT ($62,814/QALY) and FOBT ($39,171/QALY); mt-sDNA also yielded improved clinical outcomes. When reported real-world adherence rates were included for both initial stool-based screening and follow-up colonoscopy (when indicated), mt-sDNA was increasingly cost-effective compared to FIT and FOBT ($31,725/QALY and $28,465/QALY, respectively), with further improved clinical outcomes.

LIMITATIONS

Results are based on real-world cross-sectional adherence rates and may vary in the context of other types of settings. Only guideline-recommended stool-based strategies were considered in this analysis.

CONCLUSION

Comparisons of the effectiveness and benefits of specific CRC screening strategies should include both test-specific performance characteristics and real-world adherence to screening tests and, when indicated, follow-up colonoscopy.