ctDNA Testing: Can This Blood Test Detect Cancer Recurrences?

When cancer treatment ends, most women are told to “watch and wait.”

Watch for symptoms.

Wait for the next scan.

And hope everything stays clear.

But what if there was a more proactive way to monitor your body—and potentially catch cancer if it’s growing back before it shows up on a scan or causes symptoms?

That’s exactly what a ctDNA test can do.

What Is ctDNA Testing?

ctDNA stands for circulating tumor DNA—tiny fragments of DNA that are shed by cancer cells into the bloodstream.

Here’s how the process works:

1. First, a sample of your tumor from surgery is analyzed to identify specific markers or mutations that are unique to your cancer.

2. Then, your blood is tested to see if any of those same markers show up in your bloodstream.

This test can be done repeatedly over time to monitor for changes—offering a window into what may be happening in your body long before a scan would pick it up.

If the test is positive, it could mean cancer is growing again or that molecular residual disease is still present and might need treatment.

If the test is negative, it may offer peace of mind that no detectable cancer is currently present.

How Accurate Is It?

If you’ve heard of Signatera, this is one of the most commonly used ctDNA tests. While no test is perfect, ctDNA testing is impressively accurate:

Sensitivity: About 65–70% after just one post-treatment draw. That number climbs above 90% when repeated over time—helping detect recurrence earlier.

Specificity: Over 99.5%, which means if your test is positive, it’s very likely to be accurate.

I like to think of it like a smoke detector:

It’s good at alerting you early—sometimes too early—but it’s far better than finding out late.

Pros and Cons of ctDNA Testing

Like everything in medicine, there are trade-offs. Here’s what I want you to know:

Pros:

>> Early detection of recurrence—often before imaging or symptoms appear.

>> Can guide treatment decisions, like continuing medications or trying more targeted options.

>> Helps assess whether current treatment is working.

>> May encourage deeper investigation when conventional scans come back unclear.

Cons:

>> Not yet part of standardized cancer follow-up care (though that may change soon).

>> Can cause anxiety or lead to unnecessary treatment if cancer is present but wouldn’t have grown.

>> Cost—the test is expensive and not always covered by insurance.

>> A positive result doesn’t always mean recurrence will happen—it just means we need to watch more closely.

Here are Scenarios where ctDNA Testing Helps Guide Real-Life Decisions

Amy had finished treatment for breast cancer. Her scans were clear, but she couldn’t shake the feeling that something wasn’t quite right. Her ctDNA test came back positive—before any scan picked up a recurrence. That early signal allowed her team to intervene with additional treatment before the cancer grew.

Carmen was debating whether to continue her maintenance chemotherapy. The side effects were wearing her down, but she didn’t want to stop too soon. Her ctDNA test was negative multiple times over several months, giving her and her oncologist confidence that it was safe to discontinue treatment—and peace of mind that her body was truly clear.

After completing ovarian cancer treatment, Sarahwas in remission—but she couldn’t stop worrying. Every little ache made her anxious. Every scan brought sleepless nights for weeks beforehand. The results came back negative—no detectable circulating tumor DNA in her blood. It was the first time since finishing treatment that she finally exhaled. For Sarah, the result didn’t just provide medical data—it gave her a sense of safety and relief. It helped her reclaim some mental space so she could start focusing on living again, not just surviving. She continues to test every few months, and with each negative result, her confidence grows.

Because for many survivors, the hardest part isn’t the treatment—it’s the silence afterward. ctDNA testing offers one more way to hear your body’s signals and feel reassured that you’re still on the right path.

How We Use ctDNA in The Roadmap To Recovery

If you work with us inside The Roadmap To Recovery, we don’t order this test ourselves (your oncologist must do that), but we help you interpret and respond to the results.

If you receive a positive result, we:

✔️ Recommend retesting to confirm before taking action

✔️ Support you with targeted therapies like high-dose IV vitamin C, mistletoe, and other immune-supportive tools

✔️ Collaborate with your medical team to ensure your care is integrated, not isolated

Our focus is always on personalized, proactive care that empowers you with real information—not guesswork.

So, Should You Do The Test?

If you're the kind of person who wants to stay one step ahead of cancer, ctDNA testing may be worth considering. It’s not for everyone, and it’s not a crystal ball—but it can be a powerful tool in a more proactive approach to your long-term health.

And remember: a test is only part of the picture.

What you do with the information is what really matters.

Ready to Learn More?

You need to discuss the Signatera test with your oncologist (it needs to be ordered by them). But if you’re looking for additional evidence-based ways to lower your risk of recurrence and support your body after cancer treatment, I invite you to watch my free training: The First 4 Steps to Staying Cancer-Free

Inside, I walk you through simple, powerful changes that can dramatically impact your energy, digestion, immunity, and long-term health.