For many people who have completed cancer treatment, life after cancer comes with both relief and unanswered questions. The most common concerns among cancer survivors are the risk of cancer returning and how to monitor cancer recurrence.
As cancer care continues to advance, new blood-based tests are becoming available to provide additional insight into cancer at a molecular level. One of these advances is circulating tumor DNA (ctDNA) testing for minimal residual disease (MRD).
Circulating tumor DNA, or ctDNA, refers to tiny fragments of DNA that are released into the bloodstream by cancer cells. These fragments can sometimes be detected through a simple blood test.
Because ctDNA originates from cancer cells, its presence in the blood may reflect cancer activity that is too small to be seen on scans or detected through routine tests.
After surgery or other curative-intent treatments, small amounts of cancer cells may sometimes remain in the body. This is called minimal (or molecular) residual disease, or MRD.
MRD is not visible on imaging studies and does not cause symptoms. Over time, however, these microscopic cancer cells may grow and eventually become detectable as recurrent disease. ctDNA testing is designed to look for molecular signals of MRD before changes appear on scans.
ctDNA MRD testing is performed by using a blood sample. Advanced laboratory techniques analyze the sample to detect tumor-specific DNA fragments circulating in the bloodstream.
This approach allows clinicians to assess cancer-related molecular signals using a minimally invasive test. Medicare has recognized the analytical performance of ctDNA testing across several common solid tumors, noting high levels of sensitivity and specificity.
ctDNA MRD testing offers personalized prognostic information. Research across multiple cancer types has shown that detectable ctDNA after curative-intent treatment is associated with a higher likelihood of future cancer recurrence compared with undetectable ctDNA.
This information does not replace routine follow-up care, imaging, or physician visits. Instead, it provides an additional layer of insight that reflects cancer recurrence at a very early, molecular stage.
Many cancer survivors say that understanding their prognosis and chance of recurrence is one of the most important pieces of information they want after treatment. MRD testing may help provide more individualized estimates of recurrence risk than standard clinical factors alone.
Fear of cancer recurrence affects a large proportion of survivors. For some individuals, having clearer molecular information may support peace of mind, long-term planning, and more informed conversations with their health-care team.
For people who worry about cancer coming back, ctDNA MRD testing may offer a way to gain additional insight during the period after treatment when routine scans and tests are often normal. This test does not replace standard follow-up protocols such as imaging, clinical examinations, or laboratory monitoring. Instead, it is designed to complement existing surveillance by adding a molecular perspective, helping clinicians and patients look beyond visible or symptomatic changes rather than waiting until abnormalities appear on scans and proceed to earlier treatment for better outcome.
Cancer Center, Vejthani International Hospital
Call: (+66)2-734-0000 Ext. 2720, 2721
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