Liquid biopsy explained – what is it, who needs it and how do I get one?

At the end of May, NHS England rolled out a new blood test that could transform lung cancer treatment.

The liquid biopsy is a cutting-edge blood test that detects tumour DNA fragments in the bloodstream. It helps doctors spot genetic mutations quickly and decide if someone qualifies for targeted therapies. In an NHS pilot, patients who had a liquid biopsy started treatment 16 days earlier than those who had traditional tissue sampling.

In the latest episode of Talk of Hope, we speak with Professor Alastair Greystoke, co-clinical lead of the ctDNA pilot and honorary medical oncologist at Newcastle’s Northern Centre for Cancer Care. We also hear from Yvonne Diaz, who is living with stage 4 ALK+ lung cancer.

What is a liquid biopsy?

“A liquid biopsy is easy for patients—not so easy for clinicians,” says Prof Greystoke.

“It’s just a simple blood test. We send it off for analysis. Later-stage lung cancer releases tiny amounts of DNA into the blood. Ten or twenty years ago, our tech couldn’t detect it. Now it can.

“We take two vials of blood and get results within two weeks. These results give us a tumour profile and tell us if there’s a mutation. If there is, we can start targeted treatment immediately. We don’t need to wait.”

Physical and emotional benefits

“When I was being diagnosed, I felt awful—and anxious,” says Yvonne.

“I didn’t want to tell my children or loved ones until I knew what we were facing—and what the treatment plan was. I felt vulnerable and powerless. Anything that speeds up diagnosis is a good thing.”

Prof Greystoke adds, “Liquid biopsy also helps people who can’t have a tissue biopsy. That might be due to where the tumour is or the person’s overall health.

“Before this, we had to take a tissue sample using a bronchoscopy, ultrasound probe or CT-guided biopsy. These are invasive and often traumatic for patients.

“And then the sample had to be sent for analysis. It’s not a fast process—it’s slow, clunky, and adds to people’s anxiety.”

Who can, or should, have a liquid biopsy?

“This rollout only applies to patients in England,” Prof Greystoke explains. “Wales has a similar but different programme. Scotland and Northern Ireland don’t offer anything like this. If you’re from those countries, write to your MP. It’s unfair that only people in England benefit.

“To qualify, patients must be relatively fit, have probable lung cancer visible on a CT scan, and not have had a biopsy yet. If a biopsy has already been done, a liquid biopsy can’t be used.”

What else should patients know?

“About 80% of patients with late-stage lung cancer will get a result because of the DNA levels,” Prof Greystoke continues.

“But liquid biopsy doesn’t work well in early-stage disease where cancer is still contained in the lungs. In those cases, it’s not recommended.

“All NHS sites in England should be offering the test now. But some may not be ready yet. If you’re not offered it, ask why. Your doctor might not know about it—or may be unsure about the change.

“The patient voice is powerful. Telling your consultant this test matters to you can make a real difference. Even if it can’t help you, it might help someone else.”

Yvonne agrees: “Advocating for yourself is vital. So is learning about new treatments. Knowing what’s available means you’re less likely to miss out. You need to know your next step.

“There should be a national awareness campaign. People need to know this test exists—and when to ask for it. Otherwise, some may never get the chance.”