Researchers at the University of California, Los Angeles (UCLA) have created a blood test that may one day help detect several cancers, liver diseases and signs of organ damage. The test, called MethylScan, looks at tiny pieces of DNA circulating in the bloodstream and searches for patterns that can reveal what is happening in different organs. In an early study, the test was able to identify liver, lung, ovarian and stomach cancers, as well as several liver conditions. Researchers say this could make disease detection more affordable and less invasive.

The test is based on cell-free DNA (cfDNA), which is released into the blood when cells naturally die. These DNA fragments can carry information about the tissues they came from. Instead of only searching for cancer-causing mutations, MethylScan examines DNA methylation, chemical changes that help control how genes work. The findings, published in Proceedings of the National Academy of Sciences, suggest that blood-based DNA analysis could eventually become a useful tool for broader disease screening.

How Does The New Blood Test Work?

Every day, billions of cells in the body die and release small amounts of their DNA into the bloodstream. Most of this DNA comes from healthy blood cells, which makes it difficult to find the much smaller amount released by a tumour or damaged organ.

The UCLA team developed a method to reduce this background DNA before the sample is analysed. Special enzymes remove much of the unmethylated DNA, which largely comes from blood cells. The remaining DNA is then enriched for methylated DNA associated with solid organs. This allows researchers to study the disease-related signals without having to sequence enormous amounts of genetic material. This approach could also reduce the cost of testing.

What Did The Study Find?

Researchers tested MethylScan using blood samples from 1,061 people. The participants included people with liver, lung, ovarian and stomach cancers, patients with different liver diseases, people with benign lung nodules and healthy participants. Different organs have distinct methylation patterns, and disease can alter these patterns. This gives researchers a way to identify both the presence of disease and potentially where it is coming from.

Machine learning algorithms were used to interpret the complex methylation patterns in the samples. At 98% specificity, meaning relatively few healthy people were incorrectly identified as having cancer, the test detected about 63% of cancers across all stages. For early-stage cancers, it detected roughly 55%.

The test showed particularly encouraging results in people at high risk of liver cancer, including those with liver cirrhosis or hepatitis B virus infection. In this group, it detected nearly 80% of liver cancer cases, with specificity slightly above 90%.

Researchers also found that the test could distinguish between different types of liver disease. It correctly classified conditions such as viral hepatitis and metabolic-associated liver disease in about 85% of patients. This suggests that the technology may have uses beyond cancer detection.

It May Also Show Where The Disease Began

One important feature of MethylScan is that it does not simply provide a positive or negative result. The methylation patterns can also provide clues about the tissue of origin, the part of the body producing the abnormal DNA signal.

This could be important if such tests are eventually used in routine screening. A positive blood test would still need to be followed by imaging, biopsy or other diagnostic tests. Knowing which organ may be involved could help doctors decide which investigations should come next.

Dr Wenyuan Li, a professor of pathology and laboratory medicine at UCLA and co-corresponding author of the study, "Being able to trace signals back to their source is important because a positive blood test needs to be followed by imaging or other diagnostic procedures directed at the right organ."

The researchers stressed that larger prospective clinical trials are needed to understand how accurately the test works in real-world screening populations. A blood test that detects a possible cancer signal cannot by itself confirm a diagnosis. Doctors would still need appropriate diagnostic tests to establish whether cancer or another disease is actually present.

Dr Jasmine Zhou, the study's senior author, a professor of pathology and laboratory medicine and investigator at the UCLA Health Jonsson Comprehensive Cancer Center, said, "This study demonstrates that blood-based methylation profiling can deliver clinically meaningful information across multiple diseases. It's an exciting advancement that brings us closer to realizing the dream of a single assay for universal disease detection."

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