The FDA is considering a screening tool that would be able to detect numerous types of cancer through one blood test
By Deborah Jeanne Sergeant
Screening for breast, cervical, colorectal and lung cancers has become widespread and is efficacious for early detection and treatment.
But what if more cancers could be caught early through screening?
And what if the screening were as simple as a blood test?
The FDA is considering Galleri (pronounced like “gallery”), a screening tool that would be able to detect numerous types of cancer through one blood test before the patient experiences noticeable symptoms. Currently, Galleri and a similar test, Cancerguard, can be ordered under certain circumstances, but further FDA approval would prompt coverage by Medicare and commercial insurers.
A broader spectrum of screening can make a difference in cancer deaths.
“Close to 70% of deaths from cancer are from cancers we don’t have screening tests for,” said Robert Smith, PhD, senior vice president of early cancer detect science at the American Cancer Society.
Detecting these cancers through standard diagnostic tools relies on first identifying symptoms that can indicate cancer. Unfortunately, these are often missed because of how seldom patients see their primary care provider, whether they mention these symptoms and whether the provider advises further testing or a “wait-and-see” approach.
Insurance covering the cost of routine Galleri or Cancerguard screening depends upon whether this approach would result in lives saved. Randomized trials to determine this would be very costly, time-consuming and a long-term effort.
Smith said that using a broad-spectrum blood screening test may make it more difficult for patients to fit in their regular screening. Some may balk at having to schedule yet another health appointment.
But Smith does like the appeal of screening for numerous types of cancer with one blood test.
“They completed a trial a year ago and are just publishing their findings,” Smith said. “They observed a reduction in stage 4 cancer and increase in stage 1-3 cancers.”
This may indicate that the screening helps catch cancer earlier, which can often mean better chances of beating cancer, “but it’s premature to draw conclusions about the success,” Smith warned. “We’re watching the results of the follow-up over time.”
One of the drawbacks for insurance companies is that the broad-spectrum blood tests screen for less common cancers.
Statistically, it would detect fewer cancers than the tried-and-true screenings for the more common breast, cervical, colorectal (colon) and lung cancers.
But Smith said that of the blood test screening cancers, “they’re not rare if put all together. You have a 50% chance of developing cancer in a lifetime. We can’t say when. Cancer is quite common and the leading cause of death under 85, leading cause of premature death. You could argue if these tests are successful, the price of the tests would likely be a good buy.”
Implementing a roll-out of the cancer blood test screening would involve widening the capacity for phlebotomy so the healthcare system would have sufficient personnel to draw patients’ blood. Like most other healthcare roles, the field of phlebotomy is experiencing a significant shortage. There’s also a need for more laboratory technicians to process samples.
Smith could also foresee an inequity for patients in that some people are uninsured, underinsured or live far away from blood draw site.
“A lot of advanced implementation planning should be done right now to think of what challenges would we face to implement these tests,” he said.
He anticipates that if broad-spectrum cancer blood tests become widely available, AI may help as a tool for humans in sample analysis as is the case for radiology images.
The healthcare system would also need to prepare for a tidal wave of positive results. As more cancers are caught early, more patients would require treatment. Providers would need to offer counseling as to the importance of follow-up. The healthcare system would need sufficient personnel to treat patients.
“Close to 50% of patients with a positive stool test don’t get a follow-up colonoscopy,” Smith said. “We have long waiting periods to get a screening colonoscopy. There are delays between diagnostic and treatment because of the coordination across many specialty groups. We would need to know what that would look like if these tests are proven effective.”
Smith would also like to see more patients using the current screening tools currently available.
Detecting the presence of about 50 cancer types
Ashley Hein, chemistry supervisor at Oswego Health, voiced enthusiasm for a wider array of blood tests available for cancer testing.
“History has shown the benefits of laboratory testing for screening, diagnosing, and monitoring a wide variety of malignancies,” she said. “The advantages are numerous: minimally invasive testing, fast turnaround times and a fairly cost-effective use of bloodwork to aid in the diagnosis of cancer.”
Galleri would be able to detect the presence of about 50 cancer types, which Hein said is both important for its scope and also because “if a screen is positive, the panel can also predict what researchers are calling the ‘cancer signal origin’ or the source—tissue of the potential cancer. It is another hopeful sign that Congress will allow Medicare to reimburse the cost of multi-cancer detection testing, such as Galleri.”
She cautioned that results from blood tests like Galleri are not diagnostic, meaning that further confirmation such as scans, biopsies and additional bloodwork would be necessary to affirm the presence of cancer. There’s also the chance of false positives (indicating cancer where no cancer is present) and false negatives (indicating an absence of cancer where cancer is present).
“Weighing the pros and cons is always necessary when evaluating the success of a new laboratory method,” Hein said. “Galleri is no different, but so far it seems the benefits may outweigh the cons and ultimately help people access better, faster screening methods for early cancer detection.”