Cancer Screening and Multi-Cancer Early Detection Tests

Two different things

Established screening tests look for one cancer type and have been studied for whether they reduce deaths. Multi-cancer early detection (MCED) tests check a blood sample for signs of many cancers at once. The American Cancer Society (ACS) says MCED tests do not diagnose cancer: a positive result needs more tests to confirm whether cancer is present and where. [1] This page is information only and does not recommend any screening schedule for you.

Evidence labels: established, promising but limited, mixed, insufficient evidence, no good evidence of benefit, evidence of harm, marketing claim. Established screening has established guideline support in the groups named below. For MCED tests, benefit on the main trial outcome was not shown, as explained below.

Established screening: what the US Preventive Services Task Force says

• Colorectal cancer (2021): screen adults 50 to 75 (grade A) and 45 to 49 (grade B); for ages 76 to 85, offer selectively (grade C). [2]
• Breast cancer (2024): biennial mammography for women 40 to 74 (grade B); evidence is insufficient for women 75 and older (grade I). [3]
• Lung cancer (2021): annual low-dose CT for adults 50 to 80 with a 20 pack-year smoking history who smoke or quit within 15 years (grade B), stopping when health limits life expectancy or ability to have surgery. [4]

Other cancers, including cervical and prostate, have their own guidance that this page does not cover. Talk with your clinician about which screening applies to you; see Preventive Care, Vaccines and Screening in Older Adults.

Multi-cancer early detection tests

Regulatory status. The ACS says MCED tests have not been cleared or approved by the FDA, although some are available as lab-developed tests under CLIA regulations, which doctors can order. It says they do not replace current screening tests, most insurance does not cover them, and out-of-pocket cost is typically at least several hundred dollars. [1] This reflects an ACS page revised October 2, 2025; we did not read the FDA's own page, so check current status. Laws and rules change.

The randomized trial. NHS-Galleri in England randomized 142,250 people aged 50 to 77 (a test-and-usual-care group versus stored blood) across up to three annual rounds. The primary endpoint, stage III or IV cancer incidence across 12 prespecified cancer types, did not differ significantly (rate ratio 1.03; 95% CI 0.92 to 1.14). Stage IV incidence had a rate ratio of 0.86 (95% CI 0.74 to 1.00). Trial-related adverse events were under 1% and none were serious. The authors say further follow-up is needed. The trial was funded by the test maker (Grail). [5]

Test performance in the trial. In a descriptive secondary analysis, positive results were returned for about 1% of participants each round. Positive predictive value was 58.0%, 50.4% and 45.8% in rounds 1 to 3, specificity 99.5% to 99.6%, and episode sensitivity 26.7% to 37.2% for all cancers (47.6% to 63.4% for the 12 prespecified types). Several authors are employed by or consult for the manufacturer. [6]

A US single-arm study. PATHFINDER 2 enrolled 35,878 people aged 50 or older with no clinical suspicion of cancer: positive predictive value was 60.3%, specificity 99.64% and episode sensitivity 39.3% for all cancers, with a cancer detection rate of 0.54%. About 0.6% had an invasive procedure after a positive test. It was not randomized, and the authors say randomized trials and longer follow-up are needed to assess clinical utility. [7]

Reading these numbers. A positive predictive value near 50% to 60% means roughly four to five in ten positive results were not confirmed cancer in those studies, and a low sensitivity means many cancers were missed. A review of MCED tests describes risks including false positives and negatives, overdiagnosis and overtreatment, psychological and economic harms, and widening inequities. [8]

Label: promising but limited for detection of some cancers; insufficient evidence that screening with MCED tests reduces late-stage cancer or deaths. Whether population screening trials affect health-system capacity was examined too: regions in the NHS-Galleri trial saw a modest rise in diagnostic delay for some suspected cancers in the first year. [9]

How to evaluate a cancer test claim

• Does it show fewer deaths or late-stage cancers in a randomized trial? Detecting more cancers is not the same.
• What are the positive predictive value and sensitivity in people like you?
• Who funded the evidence?
• Is the "detects 50 cancers" message balanced by missed cancers?
• See also Full-Body MRI and Screening in Healthy People, Longevity Clinics and Claims and Interpreting Test Results Without Overinterpreting.