(SCIENTIFIC AMERICAN) For years scientists have sought to create the ultimate cancer-screening test—one that can reliably detect a malignancy early, before tumor cells spread and when treatments are more effective. A new method reported today in Nature Communications brings researchers a step closer to that goal. By using a blood test, the international team was able to diagnose cancer long before symptoms appeared in nearly all the people it tested who went on to develop cancer.
“What we showed is: up to four years before these people walk into the hospital, there are already signatures in their blood that show they have cancer,” says Kun Zhang, a bioengineer at the University of California, San Diego, and a co-author of the study. “That’s never been done before.”
Past efforts to develop blood tests for cancer typically involved researchers collecting blood samples from people already diagnosed with the disease. They would then see if they could accurately detect malignant cells in those samples, usually by looking at genetic mutations, DNA methylation (chemical alterations to DNA) or specific blood proteins. “The best you can prove is whether your method is as good at detecting cancer as existing methods,” Zhang says. “You can never prove it’s better.”
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