IMPORT LOW
IMPORT LOW showed that treating only the part of the breast around the tumour bed, with the same simple technique and schedule, is as safe as whole-breast radiotherapy and causes fewer changes to the breast.
Overview
IMPORT LOW randomised 2,018 women with low-risk breast cancer to whole-breast radiotherapy, whole-breast with reduced dose outside the tumour bed, or partial-breast radiotherapy only, all 40 Gy in 15 fractions with standard tangential fields. Five-year local relapse was 1.1 percent after whole-breast and 0.5 percent after partial-breast treatment, non-inferior, with fewer reported changes in breast appearance (Coles and colleagues, Lancet 2017).
- 0.5 vs 1.1 out of 100 reached this endpoint at 5 years with Partial-breast radiotherapy compared with Whole-breast radiotherapy; 0.6 fewer per 100.
- On this measure the first group did worse, not better.
- This endpoint is not one of the standard survival or response measures; read it alongside the trial's primary result.
- These results apply to the people the trial enrolled: Low-risk early breast cancer: partial-breast or reduced-dose radiotherapy versus whole-breast radiotherapy, 40 Gy in 15 fractions. People in a different situation may not see the same effect.
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.
2,018 participants enrolled.
| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Local relapse at 5 yearsprimary | Partial-breast radiotherapy | 674 | 0.5% | - | - | - |
| Whole-breast radiotherapy | 674 | 1.1% |
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