Molecular residual disease testing, which looks for circulating tumor DNA in a patient’s blood to detect cancer recurrence, is extending precision oncology into post-treatment monitoring and survivorship. For health systems, the question is not whether to add another test, but whether the governance, workflows and follow-up pathways exist to use the results consistently.
During an Oct. 15 webinar hosted by Becker’s Healthcare and sponsored by Exact Sciences, now Abbott, Rick Baehner, MD, chief medical officer of Precision Oncology at Abbott Cancer Diagnostics and clinical professor of pathology at the University of California San Francisco, explained what that operating model requires.
Here are three takeaways from the session.
Note: Quotes have been edited for length and clarity.
1. MRD testing turns a single result into an ongoing process the health system has to coordinate
In solid tumors, molecular testing has largely happened at one point in time. MRD testing works differently. The first tumor-informed test requires a tumor tissue block plus a paired blood sample and takes about 28 days, Dr. Baehner said. Follow-up blood tests take about 10 days, and in colorectal cancer they may be repeated every three months.
The results carry strong prognostic weight, and repeated testing adds to it. Being lymph node-positive carries roughly a fourfold greater likelihood of cancer recurrence, Dr. Baehner said, while multiple investigators have linked detectable tumor DNA at a single time point to as much as a tenfold higher risk. Used over time, a positive result can signal a risk 50 times higher.
Dr. Baehner highlighted how this also makes care coordination more challenging. Each order triggers handoffs across pathology, phlebotomy, the testing lab and the care team. If adoption is inconsistent across providers and sites, some treatment decisions may be informed by MRD results and others may not, leading to potential variation in how patients are treated, he said.
2. Colorectal cancer is a practical place to start, and breast cancer shows what a disciplined pathway looks like
Molecular testing is already routine in colorectal cancer; evidence has grown rapidly over the past five years and National Comprehensive Cancer Network guidelines are beginning to address MRD, Dr. Baehner said. Patients are already followed for three to five years with regular carcinoembryonic antigen blood tests and imaging, which MRD could complement. Many health systems also have mature tumor boards that are used to reviewing complex molecular results.
Breast cancer offers a model for running the pathway. At many institutions, tumor boards have defined which patients qualify for Oncotype DX testing and pathology teams have been trained to select the right tissue block, Dr. Baehner said. As a result, sending tissue for the test has become almost as routine as ordering standard receptor stains. Some institutions also track how quickly samples go out and hold testing companies accountable for how quickly results come back.
“I asked physicians what type of improvement they would want in the test — I was thinking more genes, more information. And time and time again, what I heard is to decrease the turnaround time,” Dr. Baehner said.
3. Leaders should settle eligibility, sample handling, result routing and patient follow-up before the first test is ordered
Governance teams of clinicians, pathologists and administrators should decide which tumor types and stages qualify, such as node-negative stage 2 or stage 3 colorectal cancer. They should also decide what triggers an order, so results arrive when clinicians need them.
Sample handling is where Dr. Baehner sees some of the greatest variability. “It sounds rather banal, but it really is getting samples,” he said. Pathology teams need to know which block to send, and phlebotomy teams need to know which tube to use and how many to draw.
Leaders should also decide where results land, whether in a physician portal, as a PDF or as data in the EHR. They also need a plan for positive results.
“If a test came back positive tomorrow, does the physician know what they’re going to do?” Dr. Baehner said. “Have they had that conversation with the patient? Who’s going to notify the patient or take the call from the patient, as many patients now are getting the results in parallel due to changes in federal law?”
Without that planning, he said, results can become noise that adds to patient anxiety rather than information that changes a treatment decision.
Starting with one disease and building from there
With MRD testing, Dr. Baehner advised health systems to start narrow. That means choosing one disease area where evidence is most mature and guidelines are clear, defining the eligible patients and assigning accountability from ordering through results. He also encouraged bringing informatics, quality and financial stakeholders in early. As guidelines continue to evolve, health systems that build these pathways now will be better positioned to use MRD consistently across sites and disease teams.
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