A blood test can detect four different types of tumors at an early stage. The test detects circulating tumor DNA (ctDNA) in the blood and reacts to carcinomas of the lung, intestine, breast and ovary.
In a study of about 200 patients, the procedure struck 62 percent of early-stage tumors and 75 percent of later-stage tumors. However, the test still needs to be tested in larger studies, writes the team of researchers from the U.S., Denmark and the Netherlands in the journal Science Translational Medicine. A German expert speaks of a very good work by one of the leading research groups in the field.
More than 14 million people worldwide are newly diagnosed with cancer each year – but often at late stages. "Early detection and treatment are likely to be the most effective means of reducing the burden of disease and mortality from cancer," writes the team led by Victor Velculescu of Johns Hopkins University in Baltimore. For some time now, researchers have therefore been trying to detect telltale DNA snippets that are released into the blood by tumors.
Often Involved Genes Searched
To do this, the team first identified 58 so-called driver genes, which are significantly involved in many types of cancer and consist of a total of just under 81.000 building blocks. The test analyzes blood for abnormal DNA sequences of these genes that are associated with tumors.
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The researchers tested the procedure on 44 healthy people and 194 patients who had tumors of the lung, intestine, breast or ovary at various stages. Result: In the case of advanced tumors, the test detected more than three quarters of those affected. In the early stages, the average was still 62 percent – 71 percent for colorectal cancer, 68 percent for ovarian cancer and 59 percent each for tumors of the lung and breast. Also important: In all healthy participants the test did not strike.
"These analyses provide an approach for noninvasive direct identification of patients with common early-stage tumor types," the team writes. "This study shows that early detection of cancer via DNA changes in the blood is possible and that our method is a promising approach to achieve this goal," Velculescu is quoted as saying in a statement from his university. But the method needs to be confirmed in much larger studies, the researchers concede. In principle, it can be refined even further.
Too often a false all-clear
A process that could identify half to three-quarters of patients with colorectal, ovarian, lung or breast cancer would allow for more timely treatment, the team writes. This could – at least mathematically – save more than a million lives a year worldwide.
"This is the best study I have seen on the subject so far," says Holger Sultmann, head of the "Cancer Genome Research" department at the German Cancer Research Center (DKFZ) in Heidelberg. "62 percent is a good value, but it’s still not enough for diagnostics." So the test gives the all-clear to too many people wrongly.