‘The complexities are staggering.’ U.S. plans huge trial of blood tests for multiple cancers

Tests that screen seemingly healthy people for many kinds of cancer by analyzing a blood sample are starting to enter the clinic—worrying some physicians and scientists that they could do more harm than good. Now, as part of President Joe Biden’s reignited Cancer Moonshot, the National Cancer Institute (NCI) is laying plans to evaluate the promise of such tests.

Last week, NCI advisers endorsed a $75 million, 4-year pilot study enrolling at least 24,000 people to assess the tests, which mostly pick up trace amounts of DNA and proteins that tumors shed into the blood. What it shows about the feasibility of these tests, sometimes called liquid biopsies, will help NCI decide whether to launch a longer term clinical trial, in as many as 300,000 volunteers ages 45 to 70, to learn whether they save lives.

Companies such as GRAIL and Exact Sciences report their tests can detect many tumors at an early stage, when they are easiest to treat. GRAIL is already offering its $949 test, which requires a prescription, to people over age 50 and others with an elevated risk of cancer. It has also launched a 140,000-person trial in the United Kingdom. But the tests can miss cancers and produce false positives, leading to unnecessary procedures.

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