A new cancer blood test may make boost the accuracy of current screening tools and allow doctors to detect malignant mesothelioma and other hard-to-find cancers earlier.
The test is called a multi-cancer early detection (MCED) test. The US company Grail developed it and researchers at the Cleveland Clinic tested it on more than 3,500 patients. They found that it correctly identified cancer in more than half of cases. The test was even more accurate in rare cancer types for which no screening test is available.
Malignant mesothelioma was not specifically mentioned in the report. But it is an extremely rare cancer. The method used by the new cancer blood test suggests that it could be useful for finding mesothelioma, too.
The Challenge of Detecting Mesothelioma Earlier
Malignant mesothelioma is a highly aggressive cancer linked to asbestos exposure. In the US, only about 2,500 people receive a diagnosis of mesothelioma every year. Most of those cases are detected too late for treatment to do much good. Mesothelioma patients do not usually develop symptoms until the disease is very advanced.
The new cancer blood test could help doctors identify mesothelioma earlier. The earlier this cancer is diagnosed, the better the odds that treatment will help. If a mesothelioma tumor is very small, doctors may even be able to remove it completely.
Right now, patients suspected of having mesothelioma may have several kinds of tests. Imaging studies, biopsies, lung fluid tests, exams, and patient history are all part of the process. Even then, it can be hard to know for sure if the patient has mesothelioma.
The research suggests that the new cancer blood test could be a valuable addition to the mesothelioma diagnostic process.
Accuracy Good with New Cancer Blood Test
The Cleveland Clinic study of the new cancer blood test included 2,823 cancer patients and 1,254 cancer-free patients.
The test was 51.5 percent accurate at detecting certain DNA changes that can indicate cancer. The higher the cancer stage at the time of the test, the more accurate the test was. For people with Stage III cancer, the test was 77 percent accurate. That went up to 90 percent in people with Stage IV cancer.
Cancer signals were detected in 50+ cancer types. The new cancer blood test detected them accurately in more than 88 percent of patients. Just as importantly, the rate of false positive results among people who did not have cancer was just 0.5 percent.
“Finding cancer early, when treatment is more likely to be successful, is one of the most significant opportunities we have to reduce the burden of cancer,” said Dr Eric Klein, of the Cleveland Clinic, first author on the paper. “These data suggest that, if used alongside existing screening tests, the multi-cancer detection test could have a profound impact on how cancer is detected and, ultimately, on public health.”
The test is now available by prescription in the US. England’s National Health Service plans to conduct an even larger study of the new cancer blood test. That study starts this fall and will include more than 150,000 high risk people over 50.
Klein, EA, et al, “Clinical validation of a targeted methylation-based multi-cancer early detection test using an independent validation set”, June 24, 2021, Annals of Oncology, https://www.annalsofoncology.org/article/S0923-7534(21)02046-9/fulltext