A new approach to blood tests for cancer yields promising results

A blood test that examines methylation in fragments of DNA shows promise of being able to detect multiple liver diseases, including cancer.

CANCER DIGEST – Aug. 16, 2026 – A new type of blood test is showing promise of being able to detect multiple liver diseases including cancer by examining fragments of DNA that circulate in the blood, according to researchers at the University of California Los Angeles (UCLA).

The researchers led by Dr. Jasime Zhou published their findings in the April 6, 2026 journal of the Proceedings of the National Academy of Sciences. Unlike other blood tests for cancer, the new method, called MethylScan, analyzes bits of genetic material that enter the blood stream when cells die. The material is called cell-free DNA (cfDNA).

"Every day, 50 to 70 billion cells in our body die. They don't just disappear, their DNA goes into the bloodstream," Zhou said in a press release. "That means we already have information from all our organs circulating in the blood."

Using blood to detect cancer, or liquid biopsies as they are sometimes called, is not a new concept. Those tests examine a limited set of genetic fragments for DNA mutations released from tumors. Such tests are limited in scope and the amount of DNA sequencing needed can be costly.

Zhou’s team has taken a different approach. Rather than looking for mutations, they focus on DNA methylation, a process of adding methyl groups to DNA molecules to control the activity of the gene. Different tissues have distinct methylation patterns that can be shifted when cells within the tissue become diseased or cancerous.

One of the biggest challenges the UCLA team faced was narrowing down the amount of cell-free DNA to examine. Between 80 percent and 90 percent of the billions of cells that die every day secreting cfDNA are from normal blood cells. Faced with such overwhelming amount of normal DNA it becomes a needle in the haystack to find the rare fragments associated with disease or early cancer.

To overcome that obstacle the researchers used specialized enzymes to selectively cut away unmethylated DNA fragments, which come from blood cells, and developed a genome-wide panel of molecules that enriches the remaining methylated DNA from solid organs, thus reducing the background noise while boosting the targeted signal.

To test their MethylScan approach, the researchers used blood samples from 1,061 people with liver, lung, ovarian and stomach cancers, as well as people with diseases such as hepatitis B and C, and alcohol-related liver disease. There were also people who had benign lung nodules or no disease at all.

Using a form of artificial intelligence, called machine learning algorithms, the researchers were able to interpret the complex methylation patterns found in the samples.

For detecting multiple cancers the MethylScan accurately identified 63 percent of cancers across all stages, and 55 percent of early stage cancers with a specificity of 98 percent, meaning there were very few false positives.

When they used the MethylScan to monitor people at high risk for liver cancer, such as those with cirrhosis or hepatitis B, they were able to detect 80 percent of liver cancer cases with 90 percent specificity. 

An important advantage of this method of testing is that the methylation pattern identifies the tissue of origin, so that clinicians using the test will know which part of the body to focus on for further testing. A positive blood test needs to be followed by imaging or other diagnostic testing to determine the source.

The MythylScan test will need much more testing in larger clinical trials to determine how well the test performs in real-world settings, however, Zhou says the promising results in this study represent real progress toward developing a single, affordable blood test capable of detecting many different diseases earlier.

Sources: ScienceDaily press releases and Proceedings of the National