When tumors grow, they can shed DNA that is detectable in the blood. Scientists have now shown that some of this so-called cell-free DNA, or circulating tumor DNA can identify tumors up to three years before they would otherwise be diagnosed. The study, which included a small group of cancer patients, have been reported in Cancer Discovery.
It was a surprise to find DNA carrying mutations that indicate the presence of cancer so long before typical diagnosis, noted lead study author Yuxuan Wang, MD, Ph.D., an assistant professor of oncology at the Johns Hopkins University School of Medicine. "Three years earlier provides time for intervention. The tumors are likely to be much less advanced and more likely to be curable."
In this study, the researchers analyzed plasma samples that were obtained during a large, National Institutes of Health-funded study called Atherosclerosis Risk in Communities (ARIC), which assessed risk factors for cardiovascular issues like stroke and heart attack. There were 26 people in that study who had been diagnosed with cancer with six months of providing their blood sample, while eight were diagnosed within four months. In that group of eight, there were six people for whom blood samples from the previous three to three and a half years were available as well.
By analyzing these samples that had been collected so many years earlier (as well as those of other patients and controls), the investigators determined that the cancer-linked mutations in cell-free DNA were also identifiable at this time.
"Detecting cancers years before their clinical diagnosis could help provide management with a more favorable outcome," said senior study author Nickolas Papadopoulos, Ph.D., a professor of oncology, and a Ludwig Center at Johns Hopkins investigator. "Of course, we need to determine the appropriate clinical follow-up after a positive test for such cancers."
A wide array of funding sources made this project possible, including some from private foundations like Virginia and D.K. Ludwig Fund for Cancer Research, as well as many other research grants funded by the National Institutes of Health and the Department of Health and Human Services.
Sources: Johns Hopkins University, Cancer Discovery