A new blood test was able to identify more than 50 cancer types and even the particular site in the body where they were located, doing so with a high level of accuracy, in a recent study.
Publishing their findings in the Annals of Oncology, an international team of researchers led by the Dana-Farber Cancer Institute and the Mayo Clinic studied a blood test developed by GRAIL, Inc., in Menlo Park, California.
The test relies on next-generation sequencing to analyze how certain chemical units known as methyl groups are arranged on the DNA of cancer cells. Methyl groups stick to specific portions of DNA strands and help determine whether certain genes are activated. Methyl groups tend to be arranged differently on cancer DNA compared with how they’re arranged on healthy cells’ DNA. Methylation patterns, as they’re known, display an even starker contrast between how they occur on cancer DNA compared with non-cancer DNA than do genetic mutations.
“Our previous work indicated that methylation-based tests outperform traditional DNA-sequencing approaches to detecting multiple forms of cancer in blood samples,” Dana-Farber’s Geoffrey Oxnard, MD, co–lead author of the study with Minetta Liu, MD, of the Mayo Clinic, said in a press release. “The results of this study suggest that such assays could be a feasible way of screening people for a wide variety of cancers.”
The new test looks for methyl groups in the blood, which is possible because when tumor cells die, their DNA filters into the blood.
The authors of the new study used the experimental test to analyze circulating DNA from both normal and cancer cells in 6,689 blood samples, including 2,482 drawn from people diagnosed with cancer and 4,207 from people who did not have cancer.
The people with cancer had more than 50 types of malignancies, including the dozen cancers that cause nearly two thirds of cancer deaths in the United States: breast, colorectal, esophageal, gallbladder, bladder, gastric, ovarian, head and neck, pancreatic and lung cancer; lymphoid leukemia; and multiple myeloma.
Narrowing their analysis to just the 12 cancers, the study authors found that the test correctly identified the presence of cancer at a lower rate of 67.3%.
The test was more effective in identifying cancers at more advanced stages than at earlier stages. The test correctly identified cancers that were in Stage I 39% of the time, while yielding a correct identification of 69% of cancers in Stage II, 83% of cancers in Stage III and 92% of cancers in Stage IV. Overall, for Stage I through III cases of the dozen cancers as a group, the test correctly identified the cancer 44% of the time.
When the test correctly identified cancer, it also correctly identified the organ or tissue where the cancer originated at a rate of greater than 90%.
“The test can be an important part of clinical trials for early cancer detection,” said Oxnard.
To read a press release about the study, click here.
To read the study, click here.
To learn more about blood tests for cancer, click here.