Multi-cancer blood test detected 17 cancer types in PATHFINDER 2

Short Answer

The Galleri multi-cancer early detection (MCED) blood test developed by GRAIL was evaluated in about 32,000 people over age 50 in the US and Canada with no suspicion of cancer. Cancer was confirmed in about 60% of those who tested positive; however, the test caught only about 39% of the cancers diagnosed within one year. The study had no comparison group, and it has not yet been shown that the test reduces deaths from cancer. The test is awaiting FDA approval in the US; it is not part of the national screening program in Türkiye.

What was found?

The PATHFINDER 2 study, published in Nature Medicine, enrolled 35,878 people between December 2021 and July 2024; 32,007 people were included in the performance analysis.

• Cancer detection rate: 0.54%. 185 people had to be tested to find one cancer.
• Positive predictive value: 60.3%. In about 4 out of every 10 people with a positive result, no cancer was found.
• Sensitivity: 39.3% across all cancers; 69.8% for 12 prespecified cancer types with high mortality. This means a negative result does not show that there is no cancer.
• Specificity: 99.64%. A false alarm in about 4 out of 1,000 people without cancer.
• Prediction of the organ of origin: correct in 91.3% of true positives.
• Safety: after a positive result, 213 people (0.6%) underwent an invasive procedure, 90.5% of which were non-surgical; no serious study-related adverse events were reported.

The cancers detected were of 17 different types. The study did not report separate sensitivity by organ (e.g., pancreas, ovary).

Evidence label

Study type	Prospective, interventional, single-arm; no comparison group, results descriptive (no hypothesis testing)
Participants	35,878 enrolled / 32,007 analyzed; US and Canada; age 50 and over
Human / animal	Human
Peer-reviewed	Yes, Nature Medicine, September 2026
Funding	GRAIL, the test's manufacturer, designed and funded the study
Sites	Multicenter, including Mayo Clinic; the study was not led by Mayo

Limitations and other evidence

• The authors themselves state that randomized studies and longer follow-up are needed to demonstrate the test's clinical benefit.
• The 142,000-person NHS-Galleri randomized trial in England did not meet its goal of reducing late-stage cancers. Details: FDA panel says yes to the Galleri blood test: late-stage cancers were not reduced.
• An FDA advisory committee voted in favor of the test in September 2026; the test has not yet been approved. The US Preventive Services Task Force (USPSTF) does not make a recommendation for MCED tests.

What does it mean in Türkiye?

• The national cancer screening program of the Turkish Ministry of Health is limited to breast, cervical and colorectal cancer; it is free of charge through KETEMs (Cancer Early Diagnosis, Screening and Training Centers) and family physicians. Continue with these screenings.
• Multi-cancer blood tests are not part of the screening program in Türkiye and are not covered by SGK (Türkiye's Social Security Institution).
• If you are considering having the test done privately, talk to your physician in advance about which tests would be needed if the result is positive, and what they would cost.

Correction

October 8, 2026: The first version of this article, published on October 5, stated that the study was led by Mayo Clinic and cited an unrelated gut microbiome study as a source. The statements about high organ-specific sensitivity and "over 80% accuracy" did not appear in the study, and the information that the test misses most cancers was missing. The article was rewritten based on the primary source, and funding information was added.

This content is for informational purposes and does not replace individual medical advice. Make your screening decisions together with your physician.