Jul 27, 2020 17:00:00

A blood test method to detect gastric cancer and colon cancer '4 years before symptoms appear' will be developed

Since the treatment of cancer becomes more difficult as the symptoms progress, researchers have been working for many years to develop and improve test methods for early detection of cancer. A paper published in

Nature Communications , a new open-access journal, announced that noninvasive blood test methods 'can detect cancer four years before the onset of symptoms.'

Non-invasive early detection of cancer four years before conventional diagnosis using a blood test | Nature Communications
https://www.nature.com/articles/s41467-020-17316-z

Experimental Blood Test Detects Cancer up to Four Years before Symptoms Appear-Scientific American
https://www.scientificamerican.com/article/experimental-blood-test-detects-cancer-up-to-four-years-before-symptoms-appear/

Existing research on cancer screening techniques typically used blood samples from 'people who were somehow diagnosed with cancer.' Researchers have developed methods to detect cancer cells in these blood samples by examining biomarkers such as gene mutations, DNA methylation, and specific proteins contained in these blood samples.

But Kun Zhang , a bioengineer at the University of California, who is part of a research team that published a new paper, said the development process is flawed . With the conventional development method that uses a blood sample of a person who has already developed cancer, it is only possible to develop an “examination method that detects cancer with an accuracy as high as that of the existing examination”. It is difficult to develop a better method.

To solve this problem, the research team focused on blood samples of 123,000 people aged 25 to 90 years old, collected between 2007 and 2014 in Taizhou, China. Of the people who were healthy at the time of collecting the blood sample, 575 people were diagnosed with gastric cancer, esophageal cancer, colon cancer, lung cancer, liver cancer within 4 years after collection, research The team developed a new cancer test method using blood samples from 'people who were healthy at the time of collection but later had cancer symptoms.'

The cancer screening test by the blood test called ' PanSeer ' developed by the research team detects the pattern of DNA methylation in which the expression of genes changes due to the addition of methyl groups to DNA. Past studies have shown that abnormal DNA methylation patterns are a sign of various cancers, including pancreatic cancer.

PanSeer works by separating DNA from blood samples and measuring DNA methylation scores in about 500 regions that previous studies have identified as likely to indicate the presence of cancer. The machine learning algorithm then analyzes the findings and speculates that the owner of the blood sample may develop cancer.

When the research team actually analyzed about 200 blood samples that developed cancer after collection and about the same number of blood samples that were healthy after collection with PanSeer, it showed about 90% accuracy in 'future cancer It is possible to detect 'people who develop the disease.' In addition, the percentage of false positives that diagnose healthy people even after collecting blood samples as 'development of cancer in the future' was only 5%. 'We show that the blood of cancer patients has a sign that they have cancer four years before they were hospitalized,' Zhang said.

Colin Pritchard , a molecular pathologist at the University of Washington who is not involved in this study, acknowledges that the results of this study are an interesting approach to screening tests for cancer, but other research teams are independent of other subjects Pointed out that it is necessary to carry out verification. And while Usha Menon , a cancer researcher at the University of London, says the results are robust, they're just the first step in a new testing procedure.

Zhang acknowledges that further research is needed before PanSeer can be put to practical use, and he believes future studies could identify cancer types and reduce false positives. ``There are types of cancer where early detection makes a big difference,'' Zhang said, and at the time of writing the article, he is also working on methods to detect pancreatic cancer etc. that are said to be “not easy to detect early”. I told you.