# A registry of every treatment sequence patients actually receive, with outcomes

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

## TL;DR

Record, for every patient, the order of treatments and what happened, so that the most common sequences can be compared and the worst ones flagged.

## Summary

Approved drugs multiply faster than sequencing trials. A national or multi-centre registry capturing line-by-line therapy and outcomes (as the Flatiron and Dutch cancer registries partly do) with a public dashboard of sequence performance would let clinicians see which sequences are common and which look poor, and give trialists the effect sizes needed to design randomised sequence trials.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Hypothesis: Publishing sequence-level outcomes will change prescribing away from the bottom-quartile sequences within two years, measurable as a fall in their share of use.
- Rationale: Registry feedback changed practice in cardiac surgery and in Dutch colorectal cancer care. The data already exists; it is not assembled by sequence.
- Proposed test: Build the dashboard for metastatic breast and colorectal cancer in one health system; publish; measure change in sequence shares.
- Maturity: early-clinical
- Actor: data

## Sources

- Bottleneck evidence (Too many combinations to test): Palmer & Sorger, Combination cancer therapy can confer benefit via patient-to-patient variability without drug additivity or synergy (Cell 2017): https://doi.org/10.1016/j.cell.2017.11.009

## Connected records

- ideas: [Registry-embedded randomisation of treatment order in routine care](https://onco.cc/ideas/idea-tr2-pragmatic-sequence-randomisation/)
- terms: [ADC sequencing](https://onco.cc/terms/adc-sequencing/), [Real-world evidence](https://onco.cc/terms/real-world-evidence/)
- bottlenecks: [Too many combinations to test](https://onco.cc/bottlenecks/b-combination-space/), [Weak real-world evidence and registries](https://onco.cc/bottlenecks/b-real-world-evidence/)
- key papers: [Combination Cancer Therapy Can Confer Benefit via Patient-to-Patient Variability without Drug Additivity or Synergy](https://onco.cc/key-papers/paper-palmer-cell/)

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JSON: https://onco.cc/api/v1/entities/idea-tr2-sequence-registry.json