[Correspondence] Multicancer detection tests: holy grail or cautionary tale?

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Grail's Galleri multicancer detection trial, involving 140,000 UK residents, did not meet its primary goal of reducing late-stage cancers. The correspondence cautions that the disappointing results temper hopes for a single blood test that can screen for many cancers.

A single blood test that can identify most cancers remains the aspirational goal of cancer screening. The US biotechnology company Grail has been closest to developing a viable multicancer detection test. In June, 2026, the high hopes of many were dashed at the annual American Society of Clinical Oncology (ASCO) scientific meeting: Grail's landmark Galleri trial, which randomly assigned 140 000 UK residents to usual care plus multicancer detection testing versus usual care alone, failed to meet its primary endpoint—a reduction in late-stage cancers.