You Might Have Seen Healthcare Company GRAIL’s Multi-Cancer Detecting Blood Test Circling The News As Of Late. Here’s Our Breakdown Of The Test After Talking To The Experts.

Galleri is a blood test that can detect cancer signals across more than 50 different forms of the disease, according to Galleri's website. It is designed "for use in adults with an elevated risk for cancer, such as those aged 50 or older" and "is intended to be used in addition to, and not replace, other cancer screening tests your healthcare provider recommends."

Blood Tests for Early Cancer DetectionWill the New Multi-Billion Dollar Deals Actually Help Save Lives?

To get a better understanding of how the test works and what GRAIL's goals are, SurvivorNet spoke with Dr. William Cance, a distinguished scientist in medical affairs for GRAIL and the former chief medical and scientific officer of the American Cancer Society. He explained that the test's design was based on the principle that "the tumors shed their DNA into the blood."

"As a cancer surgeon and a cancer researcher, I’ve always thought of the cancer cells as these shameless criminals on the run from the law the law is Mother Nature," he said in an interview with SurvivorNet. "And I view them as so arrogant that they just have to make their presence known.

"So, they shed DNA into the blood, and that’s how we catch them."

RELATED: National Cancer Institute Deputy: 'We Don't Have Enough Information' about Cancer-Detection Blood Tests. Here's What You Should Know

That DNA, also called cell-free DNA (cfDNA), is helpful because cancer patients have increasingly high cfDNA numbers and the cfDNA from cancer cells is different from the cfDNA of healthy cells. cfDNA from cancer cells have specific methylation patterns that identify it as cancer. DNA methylation is a normal process used by cells that turns genes on and off in the human body.

"How does this cell know to go become an eye and this one become a kidney and so forth? It’s through methylation, normal methylation," Dr. Cance explained. "But these wild and crazy cancer cells methylate so much, they just start methylating and turning on all these genes, it’s like switching them on, and that’s what Grail measures.

"So, we do two things. We tell you whether there’s a signal, this common cancer signal, and then we say that this is where our origin is."

Although the test can detect multiple different cancers, GRAIL is still trying to figure out which cancers Galleri is best at detecting. That being said, Dr. Cance said Galleri was particularly good at detecting cancers of the gastrointestinal system.

What Was The PATHFINDER Study?

Now that we've broken down how Galleri works, let's take a look at how the test performed in the recently released results from the PATHFINDER study.

First off, the PATHFINDER study was a prospective, multi-center study where researchers administered the Galleri tests to over 6,600 participants who were over 50 years old and then followed these patients for 12 months after enrollment. If a participant had a negative test at enrollment but developed a cancer within the 12-month follow-up, it was counted as a false negative. If a participant tested positive and did, in fact, have a confirmed cancer, it was counted as a true positive. If a participant tested positive but did not end up having a confirmed cancer, this was considered a false positive.

It should also be noted that Galleri's performance was measured using both an earlier version of the test and a refined version which was created to "reduce the detection of pre-malignant hematologic conditions, which are fairly common, and improve prediction of the cancer signal origin," according to GRAIL's press release.

As for results, the study found the following results:

• A cancer signal was detected in 92 participants, but only 35 participants were actually diagnosed with cancers.
• Among the confirmed cancers (true positives), 71% of participants had cancer types that have no routine cancer screening available, according to GRAIL.
• Nearly half, or 48%, of the cancers found were newly developed, and found in stages 1 and 2.
• The blood test's ability to track a cancer signal back to its particular organ of origin was rated with 97% accuracy.

As you can see, this study did not research whether these tests had any effect on mortality, so further testing will be needed to determine that very important statistic.

So, What's The Takeaway For This Blood Test?

It's important to remember that you can only access this test with a prescription, and it is not approved by the FDA something GRAIL is working towards. As for whether or not this test is a game changer or not as of right now, it depends on who you ask.

For GRAIL's Dr. Cance, he feels this test is already making an immediate positive impact in the world of cancer care.

"I’ll tell you what I have observed that every single day, I see cases that make a big difference in patient outcomes already," he said. "People will say show us survival and that’s important, very important that we show, however, we are making an immediate impact today on local control."

Dr. Cance then went on to illustrate one instance of Galleri discovering someone's pancreatic cancer when the tumor was less than 1 inch large.

"Now, I've done a lot of pancreatic surgery, and I’ve never, ever seen one that small," Dr. Cance said.

Challenges to Screening for Pancreatic Cancer

But Dr. Ritu Salani, the director of gynecologic oncology at UCLA, says that although there's "a lot of potential benefit," there's also " some potential pitfalls that we need to be aware of."

"Are we able to successfully diagnose patients in earlier stages where survival is impacted, and that is not one thing that the study has yet demonstrated, so doesn’t mean that it doesn’t but they just haven’t demonstrated that yet," Dr. Salani told SurvivorNet.

Dr. Salani also mentioned that researchers would need to determine if this test is detecting cancers that we typically already detect at an earlier stage and, if so, is Galleri still helpful and will there be a place for it in regular screenings. But her "biggest concern" with Galleri is the number of false positives it detected in the PATHFINDER study given that these results could lead to unnecessary interventions or anxiety.

"Although they found some cancers detected that you know there's no screening for, they were found in relatively early stages, they also had some false positives," Dr. Salani said. "Flushing that out is gonna be really important as we move forward."

With all that being said, Dr. Salani feels strongly that she would not recommend this blood test for anyone yet.

"I don’t think this is ready for primetime use so I would not recommend it at this time," she said. "I think we need data on how it impacts survival. I think we need to understand which cancer types maybe it’s best in and most accurate in and how we can avoid those patients getting a positive test when they actually don’t have cancer."

Learn more about SurvivorNet's rigorous medical review process.