Blood tests designed to detect multiple types of cancer from a single draw. Some, like GRAIL's Galleri, analyse DNA fragments shed by cancer cells, looking for methylation patterns. Others look for proteins or metabolites. Cancerguard, a rival test developed by Exact Sciences, an American company, combines multiple approaches.
Early detection may not necessarily save lives. A crucial unknown is whether such tests predominantly spot tumours that need treatment, rather than slow-growing, harmless types best left alone. Some prostate cancers, for example, would kill the men who have them only if they live well beyond the age of 100. Finding harmless cases through screening—"overdiagnosis"—is the bane of cancer medicine. In November 2025 the expert committee that reviews evidence on screening tests for England's National Health Service recommended against universal use of the PSA blood test for prostate cancer. For every two lives extended, the committee found, around 20 men are likely to be overdiagnosed and 12 will undergo harmful treatment.
Another complication is that some cancers are more lethal than others even if found early. A trial of a blood test for ovarian cancer called CA125, conducted by England's NHS from 2001 to 2011, showed that even though the test spotted more early cases, the lethality of the cancer meant it did not save lives.
Scientific advances reported by several academic groups may soon lead to more sophisticated tests. These use less destructive ways to identify methylation, scan the entire genome for cancerous DNA changes, and analyse patterns in the physical features of DNA fragments. Such multi-pronged approaches, supported by artificial intelligence for data analysis, hold promise for identifying which cancers need prompt action and which do not.
teamwork, n.: Having someone to blame.