• Posted October 9, 2023

'Liquid Biopsy' Could Help Guide Lung Cancer Treatment

For a subset of patients with advanced lung cancer, radiation therapy can sometimes substantially extend their lives.

Now a new study hints that a blood test could be used to identify the people most likely to benefit.

Right now, there is no way to cure stage 4, or metastatic, lung cancer -- where the disease has spread beyond the chest cavity. But there are systemic (body-wide) treatments, including drugs and immune-based therapies, that can control the disease and give people more time.

There are also some patients with stage 4 cancer who are in something of an in-between stage, where their disease has spread, but to a relatively limited degree.

Doctors call that "oligometastatic" lung cancer. And clinical trials have shown that many of those patients can have long periods living cancer-free if they are given high-dose radiation focused on the specific sites of tumor spread.

The challenge, though, is figuring out which patients with oligometastatic cancer stand to benefit, said Dr. Aadel Chaudhuri, a radiation oncologist at Washington University School of Medicine in St. Louis.

As Chaudhuri explained it, the problem is this: On imaging, it can look like a patient's lung cancer has spread in a limited way, but there are actually "micrometastases" -- tiny tumors too small to be detected on a scan.

So that person might undergo radiation only to find out a few months later that the cancer has spread.

"We haven't really done them a service," Chaudhuri said. "And if anything, you could argue that the time spent delivering radiotherapy was time taken away from what could've been stronger systemic therapy."

It's a "conundrum," Chaudhuri summed up.

So in the new study, he and his colleagues asked whether a "liquid biopsy" could help. That's a type of blood test that looks for bits of tumor DNA circulating in the blood, which could be a marker of those tiny micrometastases.

The researchers analyzed records from 309 patients with oligometastatic lung cancer who had received radiation therapy after having a liquid biopsy called Tempus xF.

The investigators found that when patients had no detectable tumor DNA in their blood, they typically lived longer: Overall, their median survival was 25 months, which means that half of patients lived longer than that, and half lived for a shorter period.

The picture was different for patients who did have detectable tumor DNA before having radiation therapy. Their median survival was just under 17 months.

The findings were presented Oct. 2 at a meeting of the American Society for Radiation Oncology, in San Diego, and published online simultaneously in the journal NPJ Precision Oncology. Chaudhuri receives research funding from Tempus Labs, which makes the Tempus xF technology, and has served as an adviser to the company.

He said the findings raise the possibility that a pre-treatment blood test might identify the patients most likely to benefit from radiation therapy, and those who need systemic therapies.

But not just yet, he and other experts stressed.

"This is exciting, but it's also only the beginning," Chaudhuri said.

For one, the study was retrospective -- meaning it looked back at patient records -- and that's not the research design that proves a treatment strategy works.

There's still a need for studies that follow patients over time, and show that the blood test can indeed help guide treatment choices, said Dr. Benjamin Cooper, a radiation oncologist at NYU Langone Health in New York City.

"This is not something you can take to your doctor right now and say, 'Can we do this?'" said Cooper, who was not involved in the research.

Dr. Rohann Correa, a radiation oncologist at London Health Sciences Center in Ontario, Canada, agreed that the findings are preliminary. He also called them "exciting."

Correa noted that for some patients with oligometastatic lung cancer, radiation therapy can slow the disease "dramatically" for a long period.

"But," Correa said, "how can we do better? How can we do a better service to our patients "¦ and better select who's going to benefit and who may not?"

For now, Cooper pointed to the bigger picture: A diagnosis of stage 4 lung cancer is understandably upsetting, he said, but the disease is different for different people. And some, Cooper said, can do well with radiation therapy.

More information

The American Cancer Society has more on lung cancer treatment.

SOURCES: Aadel Chaudhuri, MD, PhD, assistant professor, radiation oncology, Siteman Cancer Center, Washington University School of Medicine in St. Louis; Benjamin Cooper, MD, assistant professor, radiation oncology, NYU Grossman School of Medicine, New York City; Rohann Correa, MD, PhD, London Health Sciences Centre, London, Ontario, Canada; presentation American Society for Radiation Oncology meeting, San Diego, Oct. 2, 2023; NPJ Precision Oncology, Oct. 2, 2023, online