Not only can the test detect cancer, but it can also identify where the cancer signal is coming from in the body. This helps medical professionals narrow down the tests that will then need to be carried out to confirm the diagnosis and start treatment. Some of the cancers found during the trial are not currently tested for either, meaning participants could start treatment earlier than would have been possible in the past. Early diagnosis of cancer increases the chances of treatment success. “Bending the cancer mortality curve will require more cancers to be detected early,” said Josh Ofman, president of GRAIL, the company behind the testing technique. The test was conducted in the United States, where more than 600,000 people die from cancer each year. “Unfortunately, the burden of cancer will increase with the demographic tidal wave, as the absolute risk of developing any cancer increases as we age,” said Offman. “However, a world of more individual cancer screening tests is simply clinically and financially untenable, as each individual screening test has a false positive rate of 5 to 10 percent.” The test his company is developing, called the Galleri test, could enable a “paradigm change” in cancer screening “by finding more types of cancer at earlier stages with a single blood test,” he added.
How does the Galleri test work?
The blood test involved a single blood sample from the patient, which is then tested for DNA methylation – one of the hallmarks of cancer. Methylation is when methyl groups – common units of organic compounds – are detected in DNA. They do not change the DNA code, but they can change the expression of genes. The test is conducted with DNA sequencing and machine learning to analyze methylation patterns in DNA from blood. This analysis can then detect cancer signals and predict where the cancer may be in the body. According to GRAIL, the Galleri test can detect signals from more than 50 types of cancer.
Detecting cancer earlier
The study, called PATHFINDER, involved 6,662 participants, all of whom were over the age of 50 and therefore at increased risk of developing cancer. A cancer signal was found in 92 participants and of those, 35 were diagnosed with 36 different cancers in total. Among the confirmed cancers, GRAIL says 71 percent had types of cancer that are not routinely screened for, such as uterine and pancreatic cancer. Forty-eight percent of the non-recurring cancers found were in early stages. Predicting where the cancer signal was coming from in the body was found to be 97 percent accurate. “The PATHFINDER study is an exciting first step toward fundamental change in the approach to cancer screening,” said Deb Schrag, chair of the Department of Medicine at Memorial Sloan Kettering Cancer Center in New York. He added that the study “provides a taste of what the future may hold” with the opportunity to screen with blood tests to detect cancers “at the earliest and most curable stages”. Jeffrey Venstrom, the chief medical officer at GRAIL, said the Galleri test – when combined with standard screening – more than doubled the number of cancers detected. These included stage I cancers of the liver, small bowel and uterus and stage II pancreatic, bone and oropharyngeal cancers. “This is particularly noteworthy given that the PATHFINDER population was heavily screened with higher than average rates for mammography, colonoscopy, and low-dose lung CT.” The results of the study were presented at the European Society for Medical Oncology Congress 2022 in Paris.
