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PRIME II confirmed in a larger and more recent population that omitting radiotherapy in older women with low-risk hormone-sensitive breast cancer raises local recurrence modestly without affecting survival.
PRIME II randomised 1,326 women aged 65 or older with hormone receptor-positive, node-negative breast cancers up to 3 cm, treated by breast-conserving surgery and endocrine therapy, to radiotherapy or none. Ten-year local recurrence was 9.5 percent without radiotherapy and 0.9 percent with it; distant recurrence, breast cancer-specific and overall survival did not differ (Kunkler and colleagues, Lancet Oncology 2015 and New England Journal of Medicine 2023).
Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.
1,326 enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Ipsilateral breast tumour recurrence at 10 yearsprimary | Endocrine therapy alone | 668 | 9.5% | - | - | - |
| Endocrine therapy plus radiotherapy | 658 | 0.9% |
Criteria as posted are in the stored snapshot. Read 2026-10-07.
ClinicalTrials.gov data courtesy of the US National Library of Medicine.
Shares IMRT / IGRT (modern external beam), Breast cancer (all types), HR-positive / HER2-negative breast cancer and the tag radiation-wave2.
Shares IMRT / IGRT (modern external beam), Breast cancer (all types), HR-positive / HER2-negative breast cancer and the tag radiation-wave2.
Shares IMRT / IGRT (modern external beam), Breast cancer (all types), HR-positive / HER2-negative breast cancer and the tag radiation-wave2.
Shares IMRT / IGRT (modern external beam), Breast cancer (all types), HR-positive / HER2-negative breast cancer and the tag radiation-wave2.
Shares IMRT / IGRT (modern external beam) and the tag radiation-wave2.
Shares IMRT / IGRT (modern external beam) and the tag radiation-wave2.
Shares IMRT / IGRT (modern external beam) and the tag radiation-wave2.
Shares IMRT / IGRT (modern external beam) and the tag radiation-wave2.
Every source this page cites, grouped by who published it. Grouping is read from the web address, not assigned by hand.
A source that has moved or gone is reported by the weekly link check. /audit/