# A public registry of cancer treatments that were later shown not to work

Source: https://onco.cc/ideas/idea-tr2-reversal-registry/  
OnCo record `idea-tr2-reversal-registry` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Keep a running, well-documented list of cancer practices and approvals that were reversed by later evidence, so the pattern of mistakes is visible and teachable.

## Summary

Medical reversals (for example high-dose chemotherapy with stem-cell rescue in breast cancer, several accelerated approvals later withdrawn, bevacizumab in breast cancer) are scattered across the literature. A curated registry with, for each reversal, the original evidence, the reversing trial, the time to reversal, the patients exposed, and the design features that allowed the error would inform regulators and teach trainees.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Analysis of the registry will identify recurring design features (single-arm evidence, surrogate endpoints, small effect sizes) that predict reversal, and regulators will cite these features in subsequent approval decisions.
- Rationale: Prasad and colleagues' reviews of reversals in general medicine changed thinking about evidence standards; oncology has enough reversals to learn systematically.
- Proposed test: Curate 100 oncology reversals with structured fields; publish the analysis of predictors; monitor citation in regulatory documents.
- Maturity: speculative
- Actor: data

## Sources

- Bottleneck evidence (Failures are hidden): Anderson et al., Compliance with results reporting at ClinicalTrials.gov (NEJM 2015): https://doi.org/10.1056/NEJMsa1409364

## Connected records

- collections: [FDA Oncology Approvals (OCE) & Novel Drug Approvals](https://onco.cc/collections/fda-approvals/)
- ideas: [A machine-readable taxonomy of why cancer drugs fail](https://onco.cc/ideas/idea-tr2-failure-taxonomy/)
- terms: [Accelerated approval](https://onco.cc/terms/accelerated-approval/)
- bottlenecks: [Failures are hidden](https://onco.cc/bottlenecks/b-negative-results/), [Knowledge reaches practice too slowly](https://onco.cc/bottlenecks/b-knowledge-diffusion/)
- key papers: [Compliance with results reporting at ClinicalTrials.gov](https://onco.cc/key-papers/paper-anderson-n-engl-j-med/)
- roadmaps: [Trial modernisation roadmap: the randomised trial → platforms and adaptive designs → decentralised, pragmatic and always-on](https://onco.cc/roadmaps/trial-modernisation-roadmap/)

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