A new developing blood test has demonstrated its ability to detect numerous types of cancer with a high degree of accuracy, according to the tests in this test. Researchers from the Dana-Farber Cancer Institute will present the results of the multicenter trial during the Congress of the European Society of Medical Oncology (ESMO), which is celebrated in Barcelona.
The analysis, developed by the GRAIL company, uses next-generation sequencing technology to analyze DNA for small chemical tags (methylation) that influence whether genes are active or inactive.
When applied to almost 3,600 blood samples, some from cancer patients, others from people who had not been diagnosed with cancer at the time of blood collection, the test successfully detected a cancer signal from the samples of patients with cancer and correctly identified tissue from where the cancer began (the tissue of origin).
The specificity of the test, its ability to return a positive result only when the cancer is actually present, was high, as was its ability to identify the organ or tissue of origin, the researchers found.
The new test looks for DNA and that cancer cells are poured into the bloodstream when they die. Unlike so-called liquid biopsies, which detect genetic mutations or other alterations related to cancer in DNA, the technology focuses on DNA modifications known as methyl groups.
Methyl groups are chemical units that can bind to DNA, in a process called methylation, to control which genes are “on” and which are “off.” Abnormal methylation patterns turn out to be, in many cases, more indicative of cancer and cancer type than mutations. The new test focuses on parts of the genome where abnormal patterns of methylation are found in cancer cells.
“Our previous work indicated that methylation-based trials exceed traditional approaches to DNA sequencing to detect multiple forms of cancer in blood samples,” explains the study's lead author, Geoffrey Oxnard of Dana-Farber. The results of the new study show that these trials are a feasible way to detect cancer in people. ”
In the study, the researchers analyzed cell-free DNA (DNA that was once confined to cells but that reached the bloodstream after cell death) in 3,583 blood samples, including 1,530 of patients diagnosed with cancer and 2,053 of people without cancer.
Patient samples comprised more than 20 types of cancer, including negative hormonal receptors of the breast, colorectal, esophageal, gallbladder, gastric, head and neck, lung, lymphoid leukemia, multiple myeloma, ovarian and pancreatic cancer.
The overall specificity was 99.4 percent, which means that only 0.6 percent of the results incorrectly indicated that cancer was present. The sensitivity of the trial to detect prespecified high mortality cancers (the percentage of blood samples from these patients who tested positive for cancer) was 76 percent.
Within this group, the sensitivity was 32 percent for patients with stage I cancer; 76 percent for those with stage II; 85 percent for stage III; and 93 percent for stage IV. The sensitivity in all types of cancer was 55 percent, with similar increases in detection by stage.
For 97 percent of the samples that yielded a result of tissue of origin, the test correctly identified the organ or tissue of origin in 89 percent of cases.
Early detection of even a modest percentage of common cancers could result in many patients who could receive more effective treatment if the test is widely used, Oxnard concludes.