Multicancer detection: diagnostic conversion is part of the evidence base

Source Summary

Agreement: I Agree Body: Dear Editor Batson and colleagues provide a clear and important statement on the evidence required before multicancer detection tests can be considered for screening programmes.1 Their emphasis on defining the use case, diagnostic work-up, unresolved positive results, harms, cost-effectiveness and feasibility is particularly welcome. One further operational point deserves emphasis. For multicancer detection, the diagnostic pathway after a positive result is not downstream implementation alone. It is part of the evidential object itself. A cancer-associated signal has limited meaning unless it can be converted into a safe clinical endpoint: diagnosis, exclusion, surveillance, or discharge. This matters especially for multicancer detection because the result may not be anatomically bounded in the way many single-cancer screening results are. It may suggest one possible cancer site, several possible sites, recurrence, or no confirmed malignancy after investigation. The performance of a screening programme will therefore depend not only on the analytical and clinical performance of the test, but also on the diagnostic conversion pathway into which the result is introduced. That pathway includes imaging, endoscopy, pathology and molecular testing. It also runs through specialist review, communication with primary care, data integration and the follow-up of unresolved positives. Variation in these components may affect timeliness, equity, patient experience, opportunity cost and ultimately the balance of benefit and harm. This has implications for evidence generation. Trials, pilots and implementation studies should, where possible, measure cancer detection and mortality-related outcomes alongside the interval from signal to diagnosis, signal to safe exclusion, signal to surveillance decision, or signal to discharge. They should also capture unresolved positive results, additional procedures, repeat investigations, tissue adequacy, diagnostic service demand, patient understanding and psychological burden. This is not a separate pathology issue. It is central to whether multicancer detection can function as screening rather than as a generator of unmanaged diagnostic uncertainty. A programme that detects earlier but cannot convert signals into timely and safe endpoints may create harm even when the front-end test performs well. Where multicancer detection is used for screening, the question is therefore not only whether a test detects cancer-associated signals. It is whether the diagnostic system can convert those signals into timely, safe and useful clinical outcomes. Reference Batson S, et al. UK National Screening Committee position statement on evidence required for multicancer detection tests. BMJ 2026. doi:10.1136/bmj-2026-089868. No competing Interests: Yes The following competing Interests: Electronic Publication Date: Sunday, June 14, 2026 - 08:33 AI use: Yes I have used AI AI use details: Drafting support was used to help structure and edit the rapid response. The author reviewed and takes responsibility for the final content. Highwire Comment Subject: UK National Screening Committee position statement on evidence required for multicancer detection tests Workflow State: Released Full Title: Multicancer detection: diagnostic conversion is part of the evidence base Highwire Comment Response to: UK National Screening Committee position statement on evidence required for multicancer detection tests Check this box if you would like your letter to appear anonymously:: Last Name: Perunovic First name and middle initial: Branko Email: [email protected] Address: UK Occupation: Consultant Histopathologist, Chief Medical Officer Affiliation: Black Country Pathology Service BMJ: Additional Article Info: Rapid response