Certain fragments of DNA shed by tumors into the bloodstream can potentially be used to noninvasively screen for early-stage cancers, monitor responses to treatment, and help explain why some cancers are resistant to therapies, according to results of an international study led by Johns Hopkins Kimmel Cancer Center investigators. The fragments, known as cell-free circulating tumor DNA (ctDNA), were detected in the blood of more than 75% of patients with advanced cancers and in at least half of patients with localized, smaller tumors that had not spread outside of the organ where the cancer originated.
Analyzing blood samples from 640 patients with various cancers, the researchers used digital polymerase chain reaction-based technology to evaluate how well the DNA fragments predicted the presence of tumors in the patients. Comparing ctDNA with circulating tumor cells (CTCs), intact cells shed from a primary tumor that circulate in the bloodstream and may lead to metastasis, researchers found that ctDNA was often present in patients without detectable CTCs. They did not identify any cases in which CTCs were detected and ctDNA was absent.
Investigators say the work, published in Science Translational Medicine, provides strong evidence that ctDNA could be used as a “personalized biomarker” test and cancer screening tool.
“We’re already very good at treating and curing cancer when it is localized,” says lead study author Chetan Bettegowda, MD, PhD. “But we wanted to develop a noninvasive technology to enhance detection of cancer at an early stage, and we feel this is an exciting starting point for further work using this method.”
