Researchers have developed a blood test that may help doctors detect if melanoma, a dangerous form of skin cancer, is coming back—possibly months before it would be visible on traditional scans.
The test works by measuring tiny bits of DNA shed by tumor cells into the bloodstream, offering a new and less invasive way to monitor the disease.
The study, led by scientists at NYU Langone Health and the Perlmutter Cancer Center, focused on stage III melanoma.
In this stage, cancer has spread from the skin to nearby lymph nodes, and even after surgery to remove the lymph nodes, the disease can be hard to track.
This research, published in The Lancet Oncology, is the largest study so far to test whether a gene-based blood test can accurately predict when melanoma might return.
The test looks for circulating tumor DNA (ctDNA)—fragments of cancer-specific genetic material that break off from tumor cells as they die and enter the bloodstream.
In nearly 600 patients from Europe, North America, and Australia, researchers found that about 80% of those who had detectable ctDNA in their blood before starting treatment went on to experience cancer recurrence.
The disease returned more than four times faster in these patients compared to those who didn’t have detectable levels of ctDNA.
Lead author Mahrukh Syeda, a research scientist in NYU’s Department of Dermatology, explained that the higher the levels of ctDNA in a patient’s blood, the faster the cancer came back.
She believes this kind of test could help doctors identify patients who are at greater risk and need more aggressive or closely monitored treatment.
The research team also found that patients who developed detectable ctDNA during treatment—at three, six, nine, or 12 months—were very likely to experience a recurrence.
This suggests that the reappearance of ctDNA after initially testing negative may be a warning sign that the cancer is returning or worsening.
Unlike CT scans or X-rays, which may miss early signs of recurrence, especially after lymph node removal, ctDNA testing offers a real-time glimpse into what’s happening at a molecular level. It can act as a direct signal that cancer cells are still present in the body.
Senior author Dr. David Polsky, a dermatologist and professor at NYU, said the test provides clearer answers than traditional methods that examine pieces of tumor tissue under a microscope. While tissue-based tests can suggest risk, ctDNA tests can directly confirm whether the disease has returned.
Still, the researchers caution that the test isn’t perfect. In some cases, patients whose blood tested negative for ctDNA still had their cancer come back. To improve accuracy, the team plans to develop even more sensitive tests and explore how using ctDNA results in real-time treatment decisions might improve survival and quality of life for patients.
If successful, this blood test could offer hope to thousands of people battling melanoma by catching early signs of recurrence—and giving doctors a better chance to stop it in its tracks.
Source: NYU.
