Multi-cancer early detection (MCED) blood tests can detect a cancer signal from circulating cell-free DNA (cfDNA). PATHFINDER was a prospective cohort study investigating the feasibility of MCED testing for cancer screening. In this prospective cohort study done in oncology and primary care outpatient clinics at seven US health networks, a convenience sample of adults aged 50 years or older without signs or symptoms of cancer consented to MCED testing. GRAIL collected blood analyzed cfDNA, and returned the results to the participants’ doctors. If a methylation signature indicative of cancer was detected, predicted cancer signal origin informed diagnostic assessment. The primary outcome was the time and extent of, diagnostic testing required to confirm the presence or absence of cancer. 

Detailed findings from the PATHFINDER study of its MCED blood test were published in The Lancet in October 2023.  The results presented at ASCO 2024 were as follows:

• MCED testing detected a cancer signal from both new primary and recurrent cancers in cancer survivors for whom multiple years had elapsed since their original diagnosis when surveillance guidance can be unclear

• MCED testing preferentially detects generally more aggressive cancers with higher tumor shedding, most of which also do not have available screening

• The majority of diagnosed cancers with no signal detected by MCED were early stage and in tumor types that are known to be associated with lower tumor DNA shedding

• The MCED test had high specificity. Resulting in a low false positive rate, and high CSO accuracy, regardless of prior cancer history

• Taken together, these data indicate that MCED testing in cancer survivors can detect a cancer signal in individuals without symptoms or signs of cancer and earlier in the disease course, when patients may be more likely to respond to treatment.

• While MCED tests should not replace standard screening and long-term surveillance, their use can be considered in cancer survivors, especially in the years after completing treatment

KOL insights

“The PATHFINDER trial gave us a glimpse into the future of cancer, early detection, and cancer screening and showed us how a multi-cancer early detection blood test can have tremendous potential to impact patient outcomes” – Expert Opinion.

“The more broadly that we can get the message out about multi-cancer early detection technology, the more people can continue to study and incorporate this into clinical practice, the better for our patients”– Expert Opinion.

Conclusion

In conclusion, the study involved 6,662 adults over the age of 50 without symptoms suggestive of cancer. It demonstrated that an earlier version of GRAIL’s MCED test was able to identify numerous cancer types that currently lack recommended screening tests. The test facilitated targeted cancer diagnostic evaluations and achieved diagnostic resolution for most participants within three months. This study highlights the feasibility of using a blood test for multiple cancer screenings and lays the groundwork for large, controlled trials needed to establish clinical utility and cost-effectiveness.