An NHS Study
Arguments for different endpoints apparently resonated with the United Kingdom’s National Health Service (NHS). Three years ago, they initiated the Galleri study, a large randomized controlled trial to assess the effectiveness of Grail’s cancer test. The primary endpoint was not cancer-specific mortality, but the incidence of stage III or IV cancer.
The results are expected in 2026. But recruitment was stopped after 140,000 participants were enrolled. The NHS reported that the initial results were not convincing enough to continue the trial. Exact numbers were not disclosed.
The Galleri study deviates from the standard randomized controlled trial design for cancer screening procedures not only in terms of the primary endpoint, but also in blinding. The only participants who were unblinded and informed of their test results are those in the intervention group with a positive cancer test.
False Security
This trial design encourages participants to undergo blood tests once per year. But according to Dr. Robbins, it prevents the exploration of the phenomenon of “false security,” which is a potential drawback of the new cancer tests.
“Women with a negative mammogram can reasonably assume that they probably do not have breast cancer. But individuals with a negative cancer blood test could mistakenly believe they cannot have any cancer at all. As a result, they may not undergo standard early detection screenings or seek medical help early enough for potential cancer symptoms,” said Dr. Robbins.
To assess the actual risk-benefit ratio of the Galleri test, participants must receive their test results, she said. “Under real-world conditions, benefits and risks can come from positive and negative results.”
Upcoming Trial
More illuminating results may come from a large trial planned by the National Cancer Institute in the United States. Several new cancer tests will be evaluated for their ability to reduce cancer-specific mortality. A pilot phase will start later in 2024. “This study may be the only one with sufficient statistical power to determine whether an approach based on these cancer tests can reduce cancer-specific mortality,” said Dr. Robbins.
For the new blood tests for multiple cancers, it is crucial that health authorities “set a high bar for a benefit,” she said. This, according to her, also means that they must show an effect on cancer-specific mortality before being introduced. “This evidence must come from studies in which commercial interests do not influence the design, execution, data management, or data analysis.”
This story was translated from the Medscape German edition using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version appeared on Medscape.com.