Scientists have developed a blood test that can detect cancer years before symptoms show - the science explained

Thursday, 23rd July 2020, 10:27 am
Updated Thursday, 23rd July 2020, 10:27 am
The test is able to detect five common types of cancer years before symptoms show (Photo: Shutterstock)
The test is able to detect five common types of cancer years before symptoms show (Photo: Shutterstock)

Scientists say they have created a blood test that is able to detect five common types of cancer years before any symptoms show.

The test, called PanSeer, can detect stomach, gullet, bowel, lung and liver cancer as early as four years before conventional methods, including imaging tests and biopsies.

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Is the test effective?

Scientists analysed plasma samples from 605 people who did not have any symptoms of cancer in the study, with 191 of the participants later diagnosed with the disease.

The study, published in the journal Nature Communications, also assessed specimens from a further 223 diagnosed cancer patients, as well as 200 primary tumour and normal tissue samples.

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

The study also found cancer in 88 per cent of the samples from 113 participants who had already been diagnosed with the disease.

Findings from the study showed that the test could be used to help identify patients who are at high risk of developing cancer, although the results need to be validated on a larger scale.

Kung Zhang, 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."

How does the test work?

Blood-based screening tests have become more prevalent in scientific studies in recent years, as they offer a way to assess patients for cancer without the need for invasive surgery.

The test involves identifying the telltale signs of cancer based on small levels of tumour DNA that may be circulating in the blood, helping to detect the disease even before any symptoms have occurred.

The test is also able to correctly identify healthy samples 95 per cent of the time.

While a small number of blood screening tests already exist for a number of cancer types, including colonoscopy, mammography and cervical cytology, the scientists claim their work is unique as they assessed blood samples from patients who did not already have symptoms.

As such, this allowed them to develop a test that can detect cancer signs much earlier than conventional diagnosis methods.

Further large scale studies are now required to confirm the potential of the early detection blood test, but results so far have shown that “cancer can be non-invasively detected up to four years before current standard of care.”