Medical breakthrough? Researchers believe a simple blood test might be able to detect cancer in early stages

How many lives might be saved if cancer could be detected before symptoms surface?

We may soon have the answer to that question. Researchers believe they have discovered a breakthrough that will allow doctors to discover cancer in its early stages, before symptoms surface, using genetic biomarkers.

What are the details?

As The Guardian detailed, California-based DNA sequencing company Illumina noticed something "extremely unexpected" during a blood-test experiment involving 125,000 expectant mothers seven years ago. Ten of the participating mothers produced blood with a noticeable DNA abnormality.

The abnormality was later discovered to be undiagnosed cancer.

"This was not a test developed for cancer screening. But it was evidence that it might be possible," Alex Aravanis, then Illumina's senior R&D director, told The Guardian.

The experiment resulted in the company Grail, which, backed by more than $1 billion in funding, is researching how to use blood tests to detect cancer. The tests examine blood plasma for circulating tumor DNA, or ctDNA, fragments, which scientists believe directly originate from cancerous tumors.

More from the Guardian:

Looking for ctDNA has become a viable proposition in recent years because of improvements in DNA sequencing technologies that make it possible to scan fragments and find those few with alterations that may indicate cancer. While other blood-based biomarkers are being investigated, the advantage of ctDNA is that, because it has a direct link to the tumour, it can be very specific at identifying cancer. For that reason, ctDNA is also showing promise as a way to profile and monitor advanced stage cancers, a "liquid biopsy". Early detection is a harder problem.

Early on, when the tumour is small, there is not as much ctDNA to detect. The women Illumina identified as having cancer were all late, not early stage.

Detecting cancer before symptoms surface would be significant, likely giving doctors ample time to help patients fight the disease, and theoretically, dramatically decrease the number of people who die because of cancer.

What else?

In addition to Grail, medical companies Guardant Health, CancerSEEK, and Methylscape are also researching how to detect cancer in its early stages with blood testing.

While it's not exactly clear if the results are conclusive, the medical research companies are in the process of preparing mass scientific trials to determine if, indeed, the current hypothesis can be confirmed with certainty.

If the medical trials are successful, it is not yet clear how the blood testing will work in the general public, how expensive testing will be, or what cancers the tests will be able to conclusively detect.