publication date: Jun. 12, 2020

Trials & Tribulations

As screening declines amid COVID-19, at-home stool DNA test for CRC gets high adherence in Medicare population

Paul J. Limburg

Paul J. Limburg, MD, MPH

Chief medical officer for Screening, Exact Sciences;

Consultant, Division of Gastroenterology and Hepatology, Mayo Clinic


This story is part of The Cancer Letter’s ongoing coverage of COVID-19’s impact on oncology. A full list of our coverage, as well as the latest meeting cancellations, is available here.

In the midst of the heavy burden COVID-19 has placed on the health care system, cancer remains relentless. The already difficult journey for cancer patients has become more uncertain as the ways we provide and access healthcare have changed to accommodate measures that protect both health care providers and cancer patients from COVID-19.

Finding an appropriate balance between the near-term challenges imposed by the current pandemic and the longer-term consequences of delayed health care in other areas, such as cancer screening, requires thoughtful consideration and broad-based collaboration.

Recent reports indicate that nearly one third of Americans have put off at least some component of their health care due to the current environment.1 With respect to colorectal cancer—the second leading cause of cancer death in the U.S.2—delays in preventive healh care, including colorectal cancer (CRC) screening, could lead to later-stage diagnoses and increased mortality rates, rapidly eroding years of steady progress in CRC screening, early detection and successful treatment.2

In various roles over my 20-plus year career, including practicing gastroenterologist, cancer prevention investigator, and chief medical officer for Screening at Exact Sciences, I have found that successful CRC screening requires access to accurate, acceptable tests, as well as patient and provider commitment to completing the selected screening strategy, including follow-up diagnostic evaluation, when indicated.

Each of these components is critical to consider, now more than ever, as we are faced with newly-raised questions: Are the usual CRC screening tests available in the pandemic environment? Will patients be receptive to CRC screening amidst other concerns? Will providers have the bandwidth to embrace preventive care as a priority? Even before COVID-19, it was estimated that 53,000 people would die from colorectal cancer in 2020.2 It is important that we, as a community, provide respectful and responsible guidance to these questions now, so that the benefits of timely preventive care can be optimized.

There are several guideline-endorsed test options for average-risk CRC screening, including endoscopic, radiologic, and stool-based tests. Each screening modality has strengths and limitations, leading the US Preventive Services Task Force3 and the American Cancer Society4 to offer a menu of recommended strategies without a rank order, preferring instead to emphasize patient and provider choice in selecting the option that will most likely be completed.

Noninvasive CRC screening tests, including the fecal immunochemical test (FIT) and the multi-target stool DNA (mt-sDNA or Cologuard) assay, are widely accepted and offer a way for patients to safely screen at home, both during and after the current COVID-19 pandemic.

Completion of stool-based testing now can also help to reduce the pending backlog in endoscopic and radiologic CRC screening exams that have limited availability until a new version of normalcy returns. While the pandemic has created complex challenges without easy solutions, broad-based collaboration to achieve common public health goals represents the best way forward.


Achieving colorectal cancer screening adherence

In an uncertain time where cancer screenings and other diagnostic panels have fallen by as much as 68% nationally, at-home CRC screening tests with established high adherence are of even greater relevance (Respaut R, Nelson DJ. Reuters. April 27, 2020).

Results from a recent real-world study published in the Journal of Medical Screening determined high adherence rates were achievable with the mt-sDNA test for CRC screening in a large, fully insured Medicare population—albeit looking at data collected before the current pandemic.

Among 368,494 Medicare beneficiaries with a valid mt-sDNA test order, the overall cross-sectional adherence was 71.1%.5 For comparison, a recent internal assessment of meta-analyses and retrospective cross-sectional data at Exact Sciences indicated that actual programmatic adherence for annual FIT likely ranges between 40-60%.6,7,8,9,10,11

The mt-sDNA adherence study results, which were relatively consistent regardless of age, sex, Medicare coverage type, geography, and test order date, provide a window into what can be achieved while much of the country remains sheltered in place, and as health systems and their providers work to get patients safely back into health care settings.5

Study authors speculate that “the noninvasive approach, widespread accessibility, and embedded patient navigation system likely contributed to successful test completion and can be further leveraged to accelerate realization of CRC screening participation targets.”5 The robustness of the screening navigation program that supports the mt-sDNA test may not be well appreciated.

It includes a 24/7 patient navigation system in 240+ languages designed to support users throughout their screening journey to facilitate test completion, while also making assistance available to patients with insurance coverage questions.12


Screening in the new normal

After a provider prescribes mt-sDNA, it is delivered both to and from a patient’s home, limiting their interaction with the health care system at a time when limited interaction is critically important to prevent the spread of COVID-19. Additionally, patients can request the mt-sDNA test online through licensed telehealth providers and complete their part in the screening process from home.

This offers a solution for patient populations in communities where screening rates are low, whether due to geographic or systemic barriers. These factors can be leveraged to maintain CRC screening rates while other preventive health tools may be inaccessible.


New solutions and new challenges

Regular adherence to screening with either stool-based tests or structural examinations results in a reduction in premature CRC death over a lifetime.4 Given how challenging CRC screening can be during this unprecedented time, it is imperative that health care providers offer patients screening choices with features designed to increase adherence, including the mt-sDNA test.

Beyond logistical challenges, patients may be less willing to seek preventive care at a health care facility for some time to come—recognizing the lingering anxiety or concerns for safety, especially among older populations who have been disproportionately impacted by COVID-19. Offering choice among screening modalities can provide long-term benefits for both patients and providers,13 especially when these modalities can be requested and completed without a patient leaving their home.

Relatedly, it is vitally important for patients and providers to understand the need for follow-up colonoscopy after a positive stool-based screening test. If a delay in follow-up colonoscopy could cause undue anxiety for any given patient, providers may wish to discuss the pros and cons of screening for CRC at this time. While some delay may be acceptable—new 2020 NCCN guidance for CRC screening suggested follow up happen no later than six to ten months following a positive stool-based test—care must be taken to ensure the follow-up colonoscopy occurs.14

A pre-pandemic real-world study of over 16,000 mt-sDNA users found nearly 9 in 10 average-risk patients who received a positive mt-sDNA test followed up with a diagnostic colonoscopy.15 In our new normal, the health care community should consider working together in new ways to facilitate greater connection along the screening continuum to ensure completion of care. 


Looking Ahead

We must consider the long-term impact of COVID-19 on our health care system. As we begin to re-open health care facilities, clinicians will have to prioritize endoscopy procedures based on the level of medical urgency.

Patients with a positive stool test result who need a follow-up colonoscopy should be triaged above elective screening exams, aiding in the risk stratification and timely evaluation of screen-eligible patients. Patients with a negative result should continue participating in a screening program at an interval and with a method appropriate for the individual patient.

Although high-performing screening tests can help detect cancer earlier, the impact is negligible if patients do not, or cannot, follow through and complete the full process, including diagnostic follow-up, when indicated. By working closely together, the healthcare community can eliminate many barriers to effective CRC screening and help to ensure that patients have access to their preferred test option.

If we focus on implementing features designed to increase adherence, we can ultimately improve screening rates—a truly welcome victory in the midst of our fight against the pandemic.

Disclosures: Dr. Limburg serves as chief medical officer of the Screening business unit for Exact Sciences through a contracted services agreement with Mayo Clinic. Limburg and Mayo Clinic have contractual rights to receive royalties through this agreement.

Cologuard is intended for adults 45 and older at average risk for colorectal cancer. Rx only.


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  11. Kapidzic A, Grobbee EJ, Hol L, et al. Attendance and yield over three rounds of population-based fecal immunochemical test screening. Am J Gastroenterol. 2014;109(8):1257-64.

  12. Comprehensive patient support. Cologuard HCP website. Accessed May 18, 2020. 

  13. Inadomi JM, Vigan S, Janz NK, et al. Adherence to colorectal cancer screening: A randomized clinical trial of competing strategies. Arch Intern Med. 2012:172(7):575-582.

  14. National Comprehensive Cancer Network. NCCN clinical practice guidelines in oncology—colorectal cancer screening. Version 1.2020. Updated April 22, 2020. Accessed May 18, 2020.

  15. Eckmann JD, Ebner DW, Bering J, et al. Multitarget stool DNA screening in clinical practice: high positive predictive value for colorectal neoplasia regardless of exposure to previous colonoscopy. Am J Gastroenterol. 2020;115:608-615.

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