Cancer follow-up can involve many moving parts: appointments, scans, lab work, symptoms, questions, and uncertainty about what comes next. In this educational video, a stage IV colorectal cancer survivor, Ken, shares his experience with circulating tumor DNA testing and how this testing became an additional tool his care team used during surveillance after treatment for colorectal cancer.
In this video, Ken describes how a positive ctDNA test result led his team to look more closely and ultimately identify a small area of cancer spread to his liver. After surgery, he continued ctDNA monitoring as part of his follow-up plan. He shares how receiving a negative result before scans or appointments can give him “a little bit of breathing room,” while a positive or rising result can help guide the next conversation with his oncologist.
Ken’s oncologist, John Strickler, MD, explains that ctDNA is not a replacement for standard follow-up, including imaging and laboratory testing. Instead, in the right clinical setting, repeated ctDNA testing over time may provide additional information about possible disease activity, recurrence risk, and whether further evaluation should be considered.
What you’ll hear
- How Ken’s ctDNA test result prompted further evaluation that identified a small liver recurrence
- Why ongoing ctDNA monitoring became part of his surveillance plan after surgery
- How Ken receives blood samples at home and reviews results with his oncology team
- Why trends over time may be more informative than one isolated ctDNA result
- How negative results can offer reassurance while positive or rising results may prompt additional discussion or evaluation
- Why ctDNA results should be interpreted alongside scans, laboratory studies, symptoms, and a patient’s full clinical situation
- Questions people with colorectal cancer may want to ask about ctDNA testing during follow-up care
What is ctDNA?
Circulating tumor DNA, often shortened to ctDNA, refers to small fragments of DNA from cancer cells that can sometimes be found in the bloodstream. A ctDNA test is performed using a blood sample.
For some people with colorectal cancer, ctDNA testing may be used to help inform conversations about recurrence risk or surveillance. A result does not, by itself, diagnose a recurrence or determine the next treatment. A positive result may lead a care team to consider closer monitoring or additional evaluation, while a negative result may be reassuring in the context of the person’s overall follow-up plan.
An oncologist’s perspective
Dr. Strickler emphasizes that ctDNA may be worth discussing for people with colorectal cancer when the goal is to personalize surveillance or better understand recurrence risk. He also notes that the test is not appropriate for every situation and should not replace established follow-up tools, such as CT scans and routine laboratory studies.
The most useful approach is to have a plan in place before testing. Patients and their care teams should understand:
- Why the test is being ordered
- When and how often testing may be used
- What a positive result could mean and what follow-up might be needed
- What a negative result means in the context of other tests and the individual’s cancer history
- How results will be incorporated into shared treatment and surveillance decisions
Questions to ask your care team
If you have colorectal cancer and are considering ctDNA testing, you may want to ask:
- Is ctDNA testing appropriate for my stage of colorectal cancer and my treatment history?
- What question would this test help answer in my situation?
- How would a positive result change my follow-up plan?
- What would a negative result mean for me?
- Would I still need regular scans, blood work, and appointments?
- How often might testing be done?
- Is the test covered by my insurance, and are financial-assistance options available?
- Are there clinical trials studying how ctDNA can guide cancer care that may be relevant to me?
Watch part one of Ken’s story here to learn more about his colorectal cancer experience and the role of personalized blood-based testing in his care journey.
Patient information disclaimer
Ken’s experience is personal and may not reflect the experience of every person with colorectal cancer. ctDNA testing is not appropriate for every patient and does not replace medical care, imaging, laboratory testing, or individualized recommendations from an oncology team. Talk with your doctor or other qualified healthcare professional about whether ctDNA testing is appropriate for your situation
This educational resource was made possible by Natera, OmniOncology, and The Personalized Medicine Foundation.
