Research

Blood test detects 50 types of cancer

Researchers in the USA have published today results from a study of over 4,000 people in which a blood test was shown to accurately detect more than 50 cancer types, often before any symptoms appeared.

The test was most accurate at identifying 12 especially dangerous types, including pancreatic cancers that are usually diagnosed only at a very late stage.

blood-samples

About the test

By finding ways to sequence DNA that is shed by tumours into the bloodstream, the researchers were able to identify which part of the body the tumours were in with an accuracy of 96%. Meaning that the test can tell whether someone has cancer, as well as what type of cancer.

According to Dr Geoffrey Oxnard of Boston’s Dana-Farber Cancer Institute, (part of Harvard Medical School), the test was now being explored in clinical trials. He said: “You need to use a test like this in an independent group at risk of cancer to actually show that you can find the cancers, and figure out what to do about it when you find them.”

The test uses a machine learning algorithm – a type of artificial intelligence

The researchers trained a machine learning system on blood samples from people with untreated cancer and with no cancer diagnoses. They then used the system to analyse blood samples from people with cancer and without.

They then tested the trained system on another set of samples, about half of whom had cancer.

What does this mean for pancreatic cancer?

While cancer was wrongly detected only 1% of the time, for cancers, like pancreatic cancer, a third of cancers were missed. For pancreatic cancer specifically, the sensitivity of the test was not as great for early stage cancer than later stage:

The sensitivity of a test measures how often a test correctly generates a positive result for the condition being tested for. So, we can see from the below that 63% of stage 1 cancers, 83% of stage 2 cancers were picked up by the test – that’s 54% of Stage 1 & 2 cancers that were missed.

Sensitivity of test for pancreatic cancer:

  • Stage 1 = 63%
  • Stage 2 = 83%
  • Stage 3 = 75%
  • Stage 4 = 100%

Why is this important?

Stages 1 and 2 are the early stages where potentially curative surgery could be performed, so it is essential that any test picks up pancreatic cancer at these stages.

Not accurate enough, for pancreatic cancer…

So, while this test is, on the face of it, an advance in the attempt to find a blood screening test for cancer, for pancreatic cancer it is not yet accurate enough.

The researchers have acknowledged that more work needs to be done to refine the test in many more trials, so it could be some years yet before we can really see one universal blood test for multiple cancer types, including pancreatic cancer.

*Reference for blog: https://www.annalsofoncology.org/article/S0923-7534(20)36058-0/pdf

More about research

Research into cancer is often reported in the news and it can feel as though you are being given different information every day. Our research section of the website will explain the process of research, answer some common questions about research into pancreatic cancer and help you to understand more about the stories you may read.