Scientists develop blood test that can detect cancer years before symptoms show

The PanSeer can identify five different types of cancer up to four years before signs appear.

A blood test that can spot five common types of cancer years before symptoms appear has been developed by scientists.

The test, called PanSeer, is able to detect stomach, gullet, bowel, lung and liver cancer up to four years before conventional diagnosis methods, such as imaging tests or biopsies.

According to the scientists, their findings – published in the journal Nature Communications – could help identify those at high risk of developing the disease, although the results need to be validated in larger studies.

Kun Zhang, a professor at the University of California, San Diego – and one of the authors on the study, said: “The ultimate goal would be performing blood tests like this routinely during annual health check-ups.

“But the immediate focus is to test people at higher risk, based on family history, age or other known risk factors.”

The authors analysed plasma samples from 605 people who did not show any symptoms of the disease, 191 of whom were later diagnosed with cancer.

They also looked at specimens from an additional 223 diagnosed cancer patients as well as 200 primary tumour and normal tissue samples.

The team then developed a test that was able to spot cancer in 95% of the participants who did not have any symptoms when the samples were collected and were only diagnosed with the disease later.

It also flagged cancer in 88% of the samples from 113 patients already diagnosed with the disease.

The technique involves spotting the telltale signs of cancer based on very small levels of tumour DNA circulating in the blood.

In addition, the test correctly identified healthy samples 95% of the time.

Blood tests to detect cancer have become the focus of numerous scientific studies in the recent years as they offer a way to screen patients without the need for invasive surgery.

But the researchers said their work is unique because they had access to blood samples from patients who did not have symptoms, which allowed them to develop a test that “can find cancer markers much earlier than conventional diagnosis methods”.

But the researchers said that further large-scale studies are needed to confirm the potential of the test for the early detection of cancer in individuals yet to be diagnosed.

The researchers wrote: “These results demonstrate that cancer can be non-invasively detected up to four years before current standard of care.”

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