Simple Blood Test Shows Promise in Detecting Over a Dozen Cancers

A blood test capable of detecting more than a dozen types of cancer, including some that lack routine screening methods and are often diagnosed late, has shown promise in a recent study. The multi-cancer early detection (MCED) test analyzes DNA fragments released by cells into the bloodstream, a process similar to a standard blood draw.

In a study involving nearly 36,000 individuals, the MCED test identified cancer signals in 17 different types, such as ovarian, lung, breast, and colorectal cancers. Among participants who received a positive result from the MCED test, cancer was subsequently diagnosed in 173 individuals. The test demonstrated a positive predictive value of 60.3%, meaning approximately six out of ten people with a positive result were diagnosed with cancer. Its specificity was 99.6%, indicating it accurately returned negative results for the vast majority of those without cancer.

For individuals with a true-positive result, the MCED test correctly predicted the cancer's origin in its top two potential locations about 91% of the time. A significant portion of the cancers detected by the test were types for which official screening recommendations do not currently exist.

Dr. Karthik Giridhar, a medical oncologist at the Mayo Clinic and senior author of the study, highlighted the challenge of screening for cancers without established tests. He noted that this research helps understand how a multi-cancer blood test could complement current screening methods by detecting cancer signals that might otherwise go unnoticed.

The study, published in Nature Medicine, found that among 151 participants with newly diagnosed cancers detected by the MCED test, 53% had stage 1 or 2 disease, and 71% had stage 1, 2, or 3 disease. Of these, only breast, colorectal, and lung cancers have established screening recommendations from the U.S. Preventive Services Task Force (USPSTF) at Grade A or B levels, signifying substantial or moderate benefits.

For cancers lacking official screening recommendations, detection often relies on risk factors, lifestyle, and family history. While some, like anal cancer, may be screened in high-risk groups, and others like head and neck cancers can be checked through physical exams, many, such as ovarian and fallopian tube cancers, currently lack sufficient evidence for routine population-wide screening in average-risk individuals. This often leads to later-stage diagnoses.

The MCED test evaluated in the study was an earlier version of GRAIL's Galleri MCED test. The current Galleri test is available by prescription in the U.S. The U.S. Food and Drug Administration (FDA) is currently reviewing the Galleri test's application, and an FDA advisory committee recently voted 7-2 that the test's benefits outweigh its risks. The test is marketed for individuals at elevated cancer risk and is priced at $949. GRAIL funded the study, and several authors reported financial ties to the company.