# Make skipping radiotherapy the default for very low-risk breast cancer

Source: https://onco.cc/ideas/idea-prev-omit-radiotherapy-low-risk-breast-default/  
OnCo record `idea-prev-omit-radiotherapy-low-risk-breast-default` (Idea). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Trials show older women with the lowest-risk breast cancers gain almost nothing from radiotherapy after lumpectomy. Yet most still get it. Track and reward omission.

## Summary

LUMINA, PRIME II and IDEA show low local recurrence without radiotherapy in luminal A breast tumours in older women, yet most still receive it, so this idea makes omission the default pathway, with PAM50 genomic confirmation where needed, and tracks it as a quality metric. The evidence exists; the barrier is inertia and fee-for-service incentives, so payers would measure omission rate and five-year local recurrence. The test is a stepped-wedge implementation across cancer centres with registry follow-up. Being tested at scale, it addresses the bottlenecks Overdiagnosis and false alarms, Toxicity and quality of life are undervalued and Incentives reward me-too drugs and marginal gains.

## Fields

- Kind: Idea
- Last checked: 2026-09-08
- Tags: protocol-upgrade; upgrade:proven-unevenly-used; evidence:strong
- Hypothesis: A default-omission pathway raises radiotherapy omission from about 20% to at least 60% of eligible patients with five-year local recurrence of 3% or less.
- Rationale: The evidence exists; the barrier is inertia and fee-for-service incentives.
- Proposed test: Stepped-wedge implementation across cancer centres with registry follow-up.
- Maturity: being-tested-at-scale
- Actor: payer

## Notes

- Measured adoption gap: in SEER-Medicare data for 25,723 women diagnosed from 2004 to 2015 who matched the CALGB 9343 trial criteria (aged over 70, early-stage, oestrogen receptor-positive, breast-conserving surgery), 79 per cent received radiotherapy and 21 per cent did not. Omission became more frequent over time, women diagnosed in 2015 being 2.72 times more likely to omit it than those diagnosed in 2004, and the authors conclude that overall trends did not dramatically decrease. That is the source for the baseline of about 20 per cent in this record's hypothesis.

## Sources

- Bottleneck evidence (Overdiagnosis and false alarms): Welch & Black, Overdiagnosis in cancer (JNCI 2010): https://doi.org/10.1093/jnci/djq099
- NICE guideline NG101, recommendation 1.13.7: consider not using radiotherapy for women aged 65 and over with T1N0, ER-positive, HER2-negative, grade 1 to 2 tumours who will take endocrine therapy (2018): https://www.nice.org.uk/guidance/ng101/chapter/Recommendations
- Squeo et al., Long-term impact of CALGB 9343 on radiation utilization (Journal of Surgical Research 2020): https://doi.org/10.1016/j.jss.2020.07.023

## Connected records

- ideas: [One week of breast radiotherapy in five treatments as the default after surgery](https://onco.cc/ideas/idea-pu-five-fraction-breast-default/)
- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- fronts: [Radiation Therapy](https://onco.cc/fronts/radiation/)
- institutions: [National Institute for Health and Care Excellence](https://onco.cc/institutions/nice/)
- terms: [Leaving radiotherapy out](https://onco.cc/terms/radiotherapy-omission-early-breast-cancer/), [PAM50 / intrinsic subtypes](https://onco.cc/terms/pam50/)
- trials: [LUMINA](https://onco.cc/trials/lumina/)
- bottlenecks: [Incentives reward me-too drugs and marginal gains](https://onco.cc/bottlenecks/b-incentive-misalignment/), [Overdiagnosis and false alarms](https://onco.cc/bottlenecks/b-overdiagnosis/), [Toxicity and quality of life are undervalued](https://onco.cc/bottlenecks/b-toxicity-qol/)
- key papers: [Omitting Radiotherapy after Breast-Conserving Surgery in Luminal A Breast Cancer](https://onco.cc/key-papers/paper-lumina-n-engl-j-med-2023/), [Overdiagnosis in cancer](https://onco.cc/key-papers/paper-welch-j-natl-cancer-inst/)

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