After cancer treatment, many patients are left with a haunting uncertainty: Is it really gone—and will it stay that way? Even when scans appear clear, questions linger. Now, a newer tool is helping provide more clarity. It’s called Molecular Residual Disease (MRD) testing, and it offers a more precise way to detect whether cancer may still be present or could return—especially for some of the most common types of cancer.

MRD testing is expanding rapidly to detect trace amounts of solid tumors, such as breast and colorectal cancer, among the most common cancers in the U.S. Several new MRD tests launched just this year, giving patients and their doctors a newer tool to personalize post-treatment care.

What is MRD testing?

• MRD tests are designed to detect and quantify the presence of a small amount of cancer DNA that may remain in a patient’s body after treatment, even when they appear to be cancer free, that can be detected earlier than traditional imaging methods. ^I,II

Why consider MRD testing?

• Advanced detection tools provide a more precise and personalized approach to cancer recurrence monitoring. With a simple blood test, they can provide clinical insights and help empower patients with clear, timely answers enabling them to actively participate in their care and receive the appropriate treatment guidance at the right time which may help outcomes.

Who is MRD testing for?  

• MRD testing is usually performed after initial therapy, such as surgery to determine if all the cancer was removed or to see how well a cancer has responded to chemotherapy. It can assess if any cancer DNA remains, even though a tumor may not be detectable by standard methods. ^I,II MRD testing can also be used after treatment is completed to help monitor for the earliest signs of recurrence (i.e. your cancer coming back).

How might these tests help me or a loved one?

• Tailored Chemotherapy Decisions: After surgery, MRD test results, combined with a patient’s risk of recurrence, may help oncologists determine whether chemotherapy is needed, and if so, help guide the choice of regimen and treatment length.

• More Aggressive Treatment When Needed: A positive MRD result may prompt oncologists to intensify treatment, recommending additional chemotherapy or targeted therapies to eliminate remaining cancer cells.

• Swift Action on Signs of Relapse: If MRD testing detects early signs of cancer returning, the care team may order further studies to pinpoint the source of recurrence—enabling timely, targeted intervention.

Are these tests covered by insurance?

• Medicare covers multiple MRD tests across solid tumor types, setting the precedent for additional insurance coverage. The Oncodetect™ test is covered for various stages of colorectal cancer.

About the Author: Rick Baehner, M.D., has served as Exact Science’s chief medical officer, Precision Oncology since Exact Sciences’ acquisition of Genomic Health in November 2019

Dr. Baehner is also a professor in the department of pathology at the University of California, San Francisco with subspecialty expertise in cytology, breast, and molecular pathology. He directed the Hellen Diller Molecular & Immunohistochemistry Core Laboratory for 10 years.

Dr. Baehner holds his Medical Doctorate from the University of Kansas, School of Medicine and a Bachelor of Arts in philosophy from the University of Kansas. Dr. Baehner trained at the University of California, San Francisco and is boarded in anatomic and clinical pathology. He completed fellowship training programs in surgical pathology, hematopathology, and cytology.

To ensure a seamless experience for providers and patients, Exact Sciences offers a complimentary provider welcome kit complete with ordering instructions, and a dedicated patient website and discussion guide to support the use of the Oncodetect™ test.

The Oncodetect test can be ordered alongside other Precision Oncology solutions, including the Oncotype DX® Breast Recurrence Score test, the only test proven to predict chemotherapy benefit ^1,2,3.

Additionally, Exact Sciences offers screening solutions like Cologuard® and Cologuard Plus™, first-line, noninvasive colorectal cancer tests for adults 45 and older at average risk.

References:

1. Paik S, Tang G, Shak S, et al. Gene expression and benefit of chemotherapy in women with node-negative, estrogen receptor-positive breast cancer. J Clin Oncol. 2006;24(23):3726-3734.
2. Albain KS, Barlow WE, Shak S, et al. Prognostic and predictive value of the 21-gene recurrence score assay in postmenopausal women with node-positive, estrogen-receptor-positive breast cancer on chemotherapy: a retrospective analysis of a randomised trial. Lancet Oncol. 2010;11(1):55-65.
3. Referenced with permission from the NCCN Clinical Practice Guidelines In Oncology (NCCN Guidelines^®) for Breast Cancer V.4.2025. © National Comprehensive Cancer Network, Inc. 2025. All rights reserved. Accessed April 28, 2025. To view the most recent and complete version of the guideline, go online to NCCN.org. NCCN makes no warranties of any kind whatsoever regarding their content, use or application and disclaims any responsibility for their application or use in any way.