JAMA

Multicancer blood test rollout linked to slight diagnostic lag

June 2, 2026

Clinical Takeaway: Clinicians and health systems adopting MCED screening should anticipate small increases in downstream diagnostic demand and proactively manage referral capacity to avoid delays.

As multicancer early detection (MCED) blood tests move closer to real-world implementation, health systems may need to expand diagnostic capacity to avoid unintended delays for patients undergoing cancer evaluation.

A population-based analysis tied to a large MCED screening trial found that regions implementing cell-free DNA (cfDNA) blood testing experienced modest but measurable increases in diagnostic delays for certain suspected cancers, highlighting potential system-level tradeoffs.

Using data from cancer alliance regions in England, investigators compared diagnostic intervals for patients referred with suspected malignancies in areas participating in an MCED trial versus nonparticipating regions. The analysis focused on common referral pathways, including head and neck, lung, and upper gastrointestinal cancers.

Participation in the MCED screening program was associated with a small rise in diagnostic delay rates—defined as the time from referral to confirmed diagnosis—for these cancers. The increase was statistically significant but limited in magnitude, with delays extending by only a few days on average across affected pathways, according to the study.

Importantly, the authors concluded that these delays were “unlikely to have materially affected interpretation of the MCED screening trial primary findings,” suggesting that the overall clinical promise of early detection was preserved.

The findings point to a “spillover effect,” in which increased diagnostic workups generated by screening may temporarily strain healthcare resources. As the authors noted, population-scale screening interventions “likely to affect demand for limited health care resources should consider monitoring for system-level spillover effects.”

While the delays were modest, the study underscores a key implementation challenge: balancing earlier cancer detection with the capacity of diagnostic services to absorb additional demand.

Source: Mann S, et al. (2026, May 30). JAMA. Cancer Diagnostic Delay Rates Associated With a Population-Based Screening Trial Evaluating a Cell-Free DNA Multicancer Early Detection Test