# Randomise inside the registry that already follows every patient

Source: https://onco.cc/ideas/idea-bio2-registry-embedded-randomisation/  
OnCo record `idea-bio2-registry-embedded-randomisation` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Rare cancer patients are already tracked in registries. Offering randomisation inside the registry makes trials far cheaper and lets almost anyone take part.

## Summary

Trials within cohorts, or registry-based randomised trials, use existing registry infrastructure for identification, consent, allocation and outcome capture, and have been used successfully in cardiology at a fraction of conventional trial cost. Rare cancers are ideal candidates because registries already exist, populations are dispersed, and conventional site-based trials cannot reach enough patients.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Registry-based randomisation reduces cost per randomised patient by an order of magnitude versus conventional rare cancer trials, while achieving acceptable data completeness and regulatory-grade outcome ascertainment.
- Rationale: Registry-randomised trials in interventional cardiology showed that outcome capture through linked national data can be as reliable as bespoke case report forms. The infrastructure cost is already sunk in the registry.
- Proposed test: Run one registry-randomised comparison of two standard-of-care options in a rare cancer, reporting cost per patient, data completeness and regulator or guideline acceptance of the result.
- Maturity: early-clinical
- Actor: data

## Sources

- Bottleneck evidence (Rare and paediatric cancers without markets): Gatta et al., Rare cancers are not so rare: the rare cancer burden in Europe (EJC 2011): https://doi.org/10.1016/j.ejca.2011.08.008

## Connected records

- collections: [AACR Project GENIE](https://onco.cc/collections/genie/), [ClinicalTrials.gov](https://onco.cc/collections/clinicaltrials-gov/), [SEER (Surveillance, Epidemiology, and End Results)](https://onco.cc/collections/seer/)
- cancers: [Neuroendocrine tumours](https://onco.cc/cancers/neuroendocrine/), [Sarcomas (soft tissue, bone, GIST)](https://onco.cc/cancers/sarcoma/), [Thyroid cancer](https://onco.cc/cancers/thyroid/)
- terms: [Basket, umbrella, and platform trials](https://onco.cc/terms/basket-umbrella-platform/), [Real-world evidence](https://onco.cc/terms/real-world-evidence/)
- bottlenecks: [Rare and paediatric cancers without markets](https://onco.cc/bottlenecks/b-rare-cancers/), [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: [Rare cancers are not so rare: the rare cancer burden in Europe](https://onco.cc/key-papers/paper-gatta-eur-j-cancer/)

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