September 23, 2026
I’m Dr. Diana Zuckerman, president of the National Center for Health Research. Thank you for the opportunity to speak today. Our nonprofit public health think tank does not accept funding from companies with a financial interest in our work, so we have no conflicts of interest.
It would be great to have a very accurate early screening blood test that could save lives, but Galleri has not demonstrated reliable early detection
Galleri missed about two-thirds of cancers diagnosed within 12 months – and it missed more than 85% of stage 1 cancers and more than two-thirds of stage 2. That’s not as good as a coin toss. Even stage 4 cancers were correctly detected only 60% — so how many people are going to live longer if they take this test?
We don’t have data on that. In fact, we don’t actually have data on whether these tests save lives.
Meanwhile—patients will be falsely reassured. If the test shows they don’t have any type of cancer, when they start to have symptoms there will be a tendency to delay going to the doctor – just for a “little while” — and that could be deadly.
Will the risk outweigh the benefits, especially with extremely low early-stage detection for prostate, breast, ovarian, skin, and unknown accuracy for many other cancers?
The FDA should reject the term “early detection.” Because it isn’t accurately detecting most early cancers.
The specificity over 99% sounds impressive, but the Positive predictive value tells us that 1 in 4 to 1 in 3 positive results did not lead to a cancer diagnosis within 12 months.
Of the patients who were not diagnosed with cancer after having a false result showing cancer with the Galleri screening test, almost half underwent an invasive procedure: biopsies, endoscopies, and surgery. Those patients with false-positive results waited a median of 75 days for diagnostic resolution. That’s a very long, anxious waiting period — for people who later learn they don’t have cancer. And imagine the wait for all patients if millions take these tests.
Most important: The studies do not prove that screening helps patients live longer OR
- improves quality of life;
- reduces late-stage cancer incidence;
- have benefits that outweigh harm when added to existing screening; or
- provides net benefit when repeated annually in real-world practice.
In the ideal world, where doctors have unlimited time to explain these test results to patients, and where patients understand the shortcomings of the tests, continue other screening, and don’t freak out if told the test indicates cancer, then the test would be promising. But that’s not the world we live in. The tests could easily do the opposite, as people with positive results overwhelm our healthcare system, delaying diagnoses for people with cancer.