# Follow every trial participant for 30 years through registry linkage

Source: https://onco.cc/ideas/idea-data-registry-follow-up-of-trial-participants/  
OnCo record `idea-data-registry-follow-up-of-trial-participants` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Trials stop following patients after a few years, so late side effects and late relapses are missed. Link trial participants to national records so follow-up continues automatically for decades.

## Summary

Late effects of cancer treatment (second cancers, cardiac disease, endocrine failure) appear decades later, long after trials close. The Childhood Cancer Survivor Study shows the value of long follow-up but relies on costly active contact. The proposal requires consent for registry linkage in every publicly funded trial and funds automated linkage of trial participants to cancer, death and hospital records for 30 years, with pooled analysis across trials.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Passive registry follow-up will capture more than 95 percent of deaths and second cancers in trial participants at a small fraction of the cost of active follow-up, and will detect late toxicity signals for at least one widely used regimen within five years.
- Rationale: Nordic trial groups already do this; the survival curves for several adjuvant trials were extended by a decade at negligible cost through registry linkage.
- Proposed test: Link participants from five completed cooperative-group trials to registries; compare completeness and cost with the trials' original active follow-up; report late events.
- Maturity: early-clinical
- Actor: research

## Sources

- Bottleneck evidence (Weak real-world evidence and registries): Gyawali, Hey & Kesselheim, Assessment of the clinical benefit of cancer drugs receiving accelerated approval (JAMA Intern Med 2019): https://doi.org/10.1001/jamainternmed.2019.0462

## Connected records

- ideas: [Map trial case report forms to the registry standard so trial and routine data join](https://onco.cc/ideas/idea-data-trial-to-registry-bridge/)
- fronts: [AI & Computation](https://onco.cc/fronts/ai-computation/)
- companies: [Children's Oncology Group (COG)](https://onco.cc/companies/childrens-oncology-group/), [ECOG-ACRIN Cancer Research Group](https://onco.cc/companies/ecog-acrin/), [SWOG Cancer Research Network](https://onco.cc/companies/swog/)
- bottlenecks: [Survivorship and late effects are neglected](https://onco.cc/bottlenecks/b-survivorship/), [Trial design, endpoints and cost](https://onco.cc/bottlenecks/b-trial-design/), [Weak real-world evidence and registries](https://onco.cc/bottlenecks/b-real-world-evidence/)
- key papers: [Assessment of the Clinical Benefit of Cancer Drugs Receiving Accelerated Approval](https://onco.cc/key-papers/paper-gyawali-jama-intern-med/)

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