What Cancer Thrivers Need to Know about CTC and ctDNA Tests
If you’ve been navigating life as a cancer thriver, chances are you’ve encountered blood-based tests like Circulating Tumor Cell (CTC) tests or circulating tumor DNA (ctDNA) tests. These are often referred to as a “liquid biopsy”. Since my cancer diagnosis in 2017, I’ve had these types of tests run multiple times a year. I’ve used brands like RGCC, Biocept, and Signatera, and I’ve learned a lot about what these tests can (and can’t) tell us. Today, I want to share my experiences and insights with you—from my cancer thriver perspective.
What Are CTC and ctDNA Tests?
CTC Tests: Circulating Tumor Cell tests detect whole cancer cells that have broken away from a tumor and are circulating in the bloodstream. Popular brands include RGCC and the now bankrupt Biocept. The idea is that these cells can indicate whether cancer is potentially trying to spread or is spreading. These cells could be picked up on a liquid biopsy before being seen as a new tumor on a scan.
ctDNA Tests: Circulating tumor DNA tests, like Signatera by Natera, focus on fragments of genetic material shed by cancer cells in what’s called “molecular residual disease” (MRD). These fragments often provide a more detailed snapshot of the tumor’s genetic makeup, offering clues about its behavior and potential vulnerabilities.
Why Do These Tests Matter?
For many of us, these tests represent hope—hope for a less invasive way to monitor cancer, detect recurrence early, and track treatment effectiveness. They’re often called “liquid biopsies” because they can sometimes replace or supplement traditional tissue biopsies. But they’re not without their complexities.
The Reality Behind a “Zero” on a CTC Test
One of the most common misconceptions about CTC tests is that a result of “0” means you’re cancer-free. Let me tell you from personal experience—that’s not always the case. I’ve had plenty of CTC tests (variety of brands) come back with a “0” result while still having an active tumor. And I’m not alone; many of my fellow cancer thrivers have had similar experiences.
Here’s why:
- Not All Cancers Shed CTCs: Some cancers, especially less aggressive ones, don’t shed many cells into the bloodstream.
- Testing Sensitivity: CTC tests might not detect every circulating cell. They’re a piece of the puzzle, not the whole picture.
- Tumor Biology: Even active tumors may go undetected in a CTC test if they’re not releasing cells at the time of testing the blood.
This doesn’t mean CTC tests are useless—far from it! They can still provide valuable information. But they need to be interpreted in the context of your broader health picture. Or as my integrative oncologists have always said, “We looks at your labwork TRENDS not make any major treatment decision from one single test result”.
How ctDNA Tests Like Signatera Are Different
For many, ctDNA tests feel like the next evolution of liquid biopsies. Tests like Signatera are highly personalized. They’re designed based on the unique genetic markers in your tumor, which makes them incredibly specific to your cancer. These tests can:
- Detect molecularl residual disease (MRD) after treatment.
- Predict recurrence months before imaging shows anything.
- Track treatment effectiveness by monitoring changes in ctDNA levels.
For example, during a period of effective treatment, ctDNA levels may drop significantly, giving a patient and the care team confidence that the therapy is working. On the flip side, a rise in ctDNA can help catch progression early and adjust treatment plans. In my case, we used this type of testing leading into my surgeries to build confidence that my body was in a good spot for these major invasive surgeries. We also use the Signatera test after surgery as a monitor for cancer. (All the scans, bloodwork, and doctors say I am cancer FREE!)
The Emotional Rollercoaster of Testing
Let’s talk about the elephant in the room: the emotional toll these tests can take. Waiting for results can feel emotionally overwhelming, and the outcomes can bring a mix of relief, anxiety, or even confusion. A “0” on a CTC test might make you question whether it’s accurate. A rising ctDNA level can feel like a ticking time bomb.
Over the years, I’ve learned to see these tests as tools, not verdicts. They’re there to help inform our decisions, not define our future. Easier said than done, I know, but it helps to keep the big picture in mind. As I mentioned above, it’s about seeing the TRENDS not a one time result.
What’s the Cost?
CTC and ctDNA tests can be pricey. Medicare covers some tests, like Signatera, for specific cancers and cancer stages at around $3,500 per test. Private insurance may or may not cover them, and out-of-pocket costs can add up quickly. Many companies, including Natera (the maker of Signatera), offer financial assistance programs. If you’re considering one of these tests, talk to your care team about insurance coverage and payment options. And don’t hesitate to call the company itself and talk to one of their patient advocates to get a better understanding of your potential out of pocket price before you take the test. Other than the RGCC Onconomics Plus test, I have never had to pay thousands of dollars for a CTC / ctDNA test.
My Tips for Fellow Cancer Thrivers
- Ask Questions: Make sure you understand why your doctor is recommending a specific test and what the results will (and won’t) tell you. I often coach my clients to consider before the test what you will do with the information of the results. Will this test result change anything for you? Or should this be looked at along with a bigger lens for additional testing? Also ask your doctor how often they recommend getting this type of test and what they are looking for in the results as it pertains to your particular case.
- Look at Trends, Not Snapshots: One test result is just a moment in time. It’s the trends over multiple tests that often provide the most insight. Use your peace practices to calm your mind & body if you see a result that alarms you, then contact your integrative practitioner to discuss next steps, like further testing of a different kind.
- Don’t Rely Solely on Blood Tests: These tests are valuable but should be part of a comprehensive monitoring plan that includes imaging and clinical evaluations. I have found that the full body MRI’s without contrast (I’ll share more about the two companies I have used for this) give a good initial picture that can then be used to inform if another more specific scan needs to be requested.
- Find Emotional Support: Whether it’s a trusted friend, a cancer coach, or a support group, don’t feel like you need to go through the testing process alone. Sharing your fears and hopes can lighten the load. If you need some more peace on your cancer testing journey, you may like my free download of my Top 5 Tips for More Inspiration, Hope & Peace during Cancer
- Be Proactive About Cost: Don’t be afraid to ask about financial assistance or alternative options. Knowing what type of bill you can expect is helpful in planning how often to do these type of tests throughout the year. Let your practitioner know your thoughts about the costs so you can tailor a testing plan together. Your health and peace of mind is worth it.
Moving Forward
As cancer thrivers, we’re constantly learning to balance hope and realism. Tests like CTC and ctDNA are incredible tools, but they’re not crystal balls. They’re part of a larger picture that includes our bodies, minds, and spirits.So, keep asking questions, advocating for yourself, and leaning on your community. Whether your test results bring clarity or more questions, remember: You’re more than a number on a lab report. You’re a thriver, navigating this journey with courage and grace.
The world of cancer tests can be complex and overwhelming, but you don’t have to face it alone. My 1-on-1 cancer patient coaching offers guidance and reassurance, helping you manage not just the tests but the emotions that come with them. From understanding results to making confident decisions, let’s take this journey together. Find out more here.
