New Test May Detect Lung Cancer Early, But It Is Still a Long Way Off

At last weekend’s American Society of Clinical Oncology annual meeting, GRAIL released results of a study that shows the potential for lung cancer to be detected with a blood test.

The survey evaluated 127 patients with lung cancer and 580 controls. The researchers found that more than 50 percent of the mutations that could lead to cancer could be detected in participants’ blood. The specificity of the test—that is, the ability of the test to detect specific genetic markers for cancer—was 98 percent. The assays detected between 38 and 51 percent of early-stage cancers and 87 to 89 percent of late-stage cancers. They also detected cancer-like signals in five members of the control group, two of whom were later diagnosed with cancer.

“These are promising early results, and next steps are to further optimize the assays and validate results in a larger group of people,” said Geoffrey Oxnard, M.D., from the Dana-Farber Cancer Center, who shared the results at the meeting.

However, although the media generally portrayed this news as an amazing step in the detection of cancer—and it is—many steps remain in order to turn GRAIL’s study results into a “simple blood test” and make that test affordable.

Alice Goodman, a reporter for the ASCO Post, asked Oxnard how blood analysis compared to a low-dose CT scan, which is the current screening method for lung cancer. He acknowledged that this is currently unknown. Unlike a true screening in which apparently healthy people are checked for cancer, GRAIL’s approach has to date included people whose cancer status is already known. “We can’t really make that comparison,” Oxnard said.

Oxnard added that while the blood biopsy is not yet a blood test in the traditional sense of the word, it is “a sequencing method that needs to be turned into a diagnostic”; however, it has the potential to become a simple blood test.

The exchange between Goodman and Oxnard shows how difficult it is to separate fact from hype, particularly when the media gets involved. Coverage from STAT and Forbes “did a good job in consistently indicating that these tests were a long way from being used in clinical practice,” said Richard Hoffman, M.D., of the University of Iowa Carver College of Medicine.

Some of the more breathless coverage came from The Guardian, for example, whose story “’Holy Grail of Cancer Research’: Doctors Positive About Early Detection Blood Test,” may have led the public to believe that a blood test for lung cancer is much closer to reality than it actually is.

In short, GRAIL’s study results are a step in the right direction for the diagnosis of lung cancer through liquid biopsy, but many more steps remain before the company’s findings can become an actual diagnostic test.

Read the full report from Physician’s Briefing here.