This Blood Test Screens for Cancer. Should You Vote for It?

Key Points:

• Galleri is a multi-cancer early detection blood test capable of identifying cancers from over 50 types, including some for which no current screening exists, aiming to complement rather than replace traditional screening methods.
• In a recent randomized controlled trial, Galleri showed a trend toward detecting fewer late-stage cancers but failed to achieve statistically significant results, and its impact on reducing cancer mortality remains unknown.
• The test has a positive predictive value of about 52%, meaning roughly half of positive results are false positives, which can lead to anxiety, invasive follow-up procedures, and prolonged uncertainty for patients.
• The FDA advisory committee was divided on Galleri's approval due to the lack of clear clinical utility data, though it unanimously agreed the test is safe and that benefits may outweigh risks; some members changed their votes during deliberations.
• While Galleri represents a promising advance in cancer screening technology, concerns remain about its cost, clinical effectiveness, potential overdiagnosis, and the influence of industry lobbying on its adoption in public healthcare systems.