Results from the PATHFINDER 2 trial show the Galleri test identifies 6.5 times more cancers when used with standard screenings.
GRAIL announced performance and safety results from the analysis of the full 35,878-participant cohort of its PATHFINDER 2 study. The data, presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting, indicate that the Galleri multi-cancer early detection (MCED) test significantly increases cancer detection when added to standard-of-care screenings.
The prospective PATHFINDER 2 study included adults aged 50 and older with no clinical suspicion of cancer. According to the study results, adding the test to recommended screenings for breast, cervical, colorectal, and lung cancers led to a 6.5-fold increase in the number of cancers found.
“These PATHFINDER 2 results add to the growing body of clinical evidence in a large, representative intended-use population showing that the Galleri test can meaningfully increase cancer detection beyond recommended screening with strong performance and a highly favorable safety profile,” says Josh Ofman, MD, MSHS, president and CEO-Elect at GRAIL, in a release. “Along with the NHS-Galleri trial results, these findings reinforce the clinical benefit of Galleri and its potential to transform early cancer detection at population scale.”
Detection and Staging Results
In the US, only 14% of all cancers are typically detected by guideline-recommended screening tests. In the PATHFINDER 2 study, 60% of diagnosed cancers were screen-detected. Of the new cancers identified by the MCED test, 70.9% were detected at stages I-III, which are stages where treatment with curative intent is more often possible. Additionally, 53.0% of the new cancers detected were stage I or II.
The study also evaluated the test’s ability to pinpoint the cancer signal origin. The test correctly identified the origin 91.3% of the time, which the company reports led to efficient diagnostic workups. Diagnostic resolution took a median of 48 days, and only 0.6% of all participants underwent an invasive procedure following a positive test result.
“PATHFINDER 2 provides important additional data on the performance and safety of MCED testing,” says Karthik Giridhar, MD, assistant professor of oncology at Mayo Clinic and a principal investigator on the study, in a release. “MCED tests are not a replacement for existing screening, but they have the potential to complement current approaches by helping detect cancer signals across multiple cancer types, including some for which routine screening is not currently available.”
Performance and Specificity Metrics
The Galleri test detected a cancer signal in 287 participants, leading to a cancer diagnosis in 173 individuals. This resulted in a positive predictive value of 60.3%. The test demonstrated a specificity of 99.6%, which translates to a false positive rate of less than 0.4%.
Regarding episode sensitivity—the ability to detect cancer confirmed within 12 months of the blood draw—the test showed a 69.8% sensitivity for the 12 cancers responsible for two-thirds of cancer deaths in the US. For all cancers combined, the episode sensitivity was 39.3%.
“The up to 6.5 fold improvement in screen-detected cancers with Galleri in PATHFINDER 2 study, coupled with the greater than 20% reduction in Stage 4 cancers observed in the NHS-Galleri trial, is really exciting data that help support Galleri’s performance in a diverse and representative population,” says Nima Nabavizadeh, MD, associate professor of radiation medicine at Oregon Health & Science University, in a release.
The study reported a favorable safety profile with a low rate of invasive procedures. Five study-related adverse events were reported during diagnostic evaluation, all occurring in participants with a confirmed cancer diagnosis. While anxiety temporarily increased for those with a positive test result, levels returned to baseline within 12 months.
ID 2783120 | Healthcare © Pmisak | Dreamstime.com
