A new blood test discovers some cancers four years earlier than we can do now

The test analyzes the methylation of DNA, identifying the changes that precede the appearance of the full-blown neoplasm. If it became routine, it would advance the diagnosis by years, giving patients more chance

(image: Getty Images) Cancer of the stomach, esophagus, colorectal, liver and lung. These are the forms of cancer (among the most common) that the PanSeer test developed by the University of California San Diego manages to diagnose very early, up to four years earlier than today's tests do. As described in the study just published in Nature Communications, the analysis traces changes in DNA methylation in the blood and detects, in advance of traditional tests, cancer in 95% of the samples of sick but still completely asymptomatic individuals. For authors, it could become routine screening in the future, improving patient prognosis.

Find methylated DNA

Kun Zhang's team at the University of California San Diego has been collaborating for years with other research groups to develop tests for the early diagnosis of different types of tumors: identifying a neoplasm at its beginning, in fact, affects the prognosis and increases the chances of survival since it leaves more treatment options open.

For ten years, in particular, scientists have focused on developing a technique that would help detect cancer based on a biological process called DNA methylation. In a nutshell, when DNA replicates, it undergoes changes with the addition or subtraction of chemical groups, for example methyl groups. It is a normal process but that changes when the cell undergoes a transformation in a cancerous direction, and it is these changes that are identified by the PanSeer test, which specifically seeks changes called CpG.

The study

To test the potential of this test, the researchers have drawn from the Taizhou longitudinal study , that between 2007 and 2017 has collected plasma samples from over 120 thousand participants who undergo medical checks on an annual basis .

The team has put to the test in the new test, analyzing the blood samples of 605 persons , 191 of which at some point had a diagnosis of cancer . Going back to the champions of the previous years at diagnosis, the researchers through the Pan-Seer were able to track changes to the CpG for up to four years before you get symptoms (the tumor, however, was already there, it is not a preventive test). Scientists, then, have applied the test to the samples of the other 223 patients with cancer, more than 200 samples of primary tumors and healthy tissues.

What they concluded is that it is currently PanSeer is able to detect 5 common forms of cancer in 88% of patients post-diagnosis with a specificity of 96% , and find it in 95% of samples of patients taken when they were still asymptomatic.

promising Results , which, however, must be confirmed by further large-scale studies.

“The ultimate goal would be to perform regular blood tests such as this during the health checks annual,” commented Zhang. “But the immediate goal is to test the people at highest risk, based on family history, age or other known risk factors” .