Early Detection Cancer Screening in Blood

"If we can find more Stage 1 or more early stage cancers in a population that we can't screen for currently, then that will end up having benefit."

"But I don't know that that's been proven yet. So perhaps my 'yes' is a hopeful [vote] rather than an accurate one."

Victor van Berkel, division chief of thoracic surgery, University of Louisville

 

"There's no proof that this is going to reduce your risk of dying from cancer."

"If you have a negative test, you should not feel reassured [and] continue with [cancer screenings] that have been proven."

Scott Ramsey, physician/researcher, Fred Hutchinson Cancer Center 

 

"I would still view it as an encouraging step rather than the final word on the clinical value of this type of testing." 

"Galleri has shown that we can detect signals from many different cancers with very high specificity using a simple blood test, including cancers for which we currently have no routine screening. That is an important advance.”

"[But the] real goal [is not just to find more cancers]. It is to find them early enough to change what happens to the patient."

"We still need longer-term evidence showing that this leads to fewer advanced cancers and ultimately fewer cancer deaths."

Professor Ajay Goel, chair, department of molecular diagnostics and experimental therapeutics, City of Hope  

Galleri is a blood test from California-based biotech company Grail, Inc. that screens for unique fragments of DNA shed by cancer cells. (Turgut Yeter/CBC)

 

A panel of the U.S. Food and Drug Administration has backed a controversial blood-based cancer test, but just barely, among some members of the panel who have their doubts about its reliability and others who feel that any new method that advances the detection of cancer can be useful in the arsenal of medical science's ongoing search for more and more accurate diagnostic tools. The emerging field of cancer screenings offering less invasive detection methods of the presence of a range of cancers before the appearance of symptoms, is steadily advancing.

 

In the United States the test, named Galleri, has been available for the past five years, albeit not FDA- approved. Galleri tests for DNA fragments in blood samples to indicate the presence of cancer. The manufacturer of the test, Grail, claims their product is able to detect over 50 types of cancer, inclusive of stomach, bladder, colorectal, skin and breast cancer. According to advocates the test, through early detection of cancers, has saved lives. Pointing out it can detect cancers currently not screened for, making testing more accessible. 

 

Critics on the other hand, question the efficacy of the test. A significant reduction in late-stage cancer diagnoses for patients who took the Galleri test in a major trial conducted woth the British National Health Service, failed. The Medical Device Advisory Committee of the FDA voted 6-4 on the ten-person panel just barely affirming the effectiveness of Galleri. Additionally with a 7-2 vote (one abstention) agreeing that the benefits of the test outweigh its risks. As for safety, all 10 members voted in favour.

 

As far as some members of the committee were concerned, the potential of the test to detect cancers that cannot be screened for currently, presents promise enough to support the test. Others, though voting in favour of Galleri, felt not enough data to firmly establish the test's effectiveness has been produced. The FDA will produce its own decision whether to approve the test, even as it often makes use of the  committee's guidance.

 

Galleri's manufacturer states its product should not replace existing cancer screenings, but complement them, in use for adults aged 50 and older. In February, Grail applied for pre-market approval of Galleri. According to the company the FDA is expected to render its final decision shortly. A class of multi-cancer early detection tests whose purpose is to detect a wide range of cancers before symptoms occur, has been joined by Galleri, representing a more advanced test in that category. 

 

The U.K. National Health Service is conducting a research trial to see if using the Galleri blood test can help find cancer early. (NHS-Galleri)

 

At the committee meeting William Dahut, chief scientific officer of the American Cancer Society explained that multi-cancer early detection tests offer a more efficient path in improving cancer screening than would the development of more cancer-specific-dedicated tests. "No screening test is perfect. But if we sit in a room for the next 20 years trying to find the perfect test, we have a large possibility we're going to lead to more cancer deaths."

 

According to Emil Lou, oncologist and associate professor of medicine at the University of Minnesota, research has improved our understanding of cancer signals and how to locate them in blood tests; the tests hold promise, in his opinion. The risk, however, of false-positive results and false-negative results remain, he cautioned. Patients would suffer undue stress with false positives leading to unneeded additional tests and procedures; false negatives on the other hand risk creating a false sense of security. 

 

"People might see this (and think): 'Well, I can just go do a one-time test. If it comes back negative, I have no cancers, and I don't have to do a colonoscopy'." A first-of-its-kind trial of a multi-cancer early-detection test involving over 140,000 participants through the NHS trial, found testing failed to decrease the rate of Stage 3 and 4 diagnoses of 12 cancers; the trial's main goal. 

 

A principal investigator in a separate multi-cancer early-detection trial, Scott Ramsey, physician and researcher at the Fred Hutchinson Cancer Center, said the Galleri trial's failure, funded by the National Cancer Institute, to reduce late-stage diagnoses called into question the test's effectiveness at early detection. "There's no proof that this is going to reduce your risk of dying from cancer. If you have a negative test, you should not feel reassured (and) continue with (cancer screenings) that have been proven."

 

Wellness Haus, a  private clinic in Toronto is the first in Canada to offer a new cancer screening blood test called Galleri, but questions remain about the effectiveness of the $2,100 test. CBC

 

"The Galleri test has been on my radar for years because I've had several patients go to the U.S. to get it done there."

"The test is still in its infancy. [Researchers are] still doing studies on it. So it's not something that I go and tell everybody to go do."  

Dr. Melissa Hershberg, medical director, Wellness Haus, private health clinic, Toronto

 

Dr. Eddy Lang is a professor at the University of Calgary's Cumming School of Medicine and a member of the Canadian Task Force on Preventive Health Care. (Submitted by Dr. Eddy Lang)

 

"The problem as I see it is that the test has not yet been proven to improve patient outcomes."

"Until we have studies that show that people actually live longer as a result of getting the test, I think we need to be very apprehensive about using it." 

"I think a healthy consumer skepticism is the way to go."  

Dr. Eddy Lang, University of Calgary medical school