# NSABP B-39/RTOG 0413

Source: https://onco.cc/trials/nsabp-b39/  
OnCo record `nsabp-b39` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The largest partial-breast trial found recurrence rates within one percentage point of whole-breast treatment but could not formally prove equivalence, so accelerated partial-breast irradiation is offered to selected lower-risk women rather than everyone.

## Summary

NSABP B-39/RTOG 0413 randomised 4,216 women with stage 0 to II breast cancer to whole-breast irradiation or accelerated partial-breast irradiation given twice daily over five to ten days by brachytherapy or external beam. Ten-year ipsilateral breast tumour recurrence was 4.6 percent with partial-breast and 3.9 percent with whole-breast treatment; the hazard ratio's confidence interval crossed the equivalence margin, so equivalence was not established, although the absolute difference was small (Vicini and colleagues, Lancet 2019).

## Fields

- Kind: Trial
- Status: negative
- Last checked: 2026-09-16
- Tags: radiation-wave2
- Registry id: NCT00103181
- Phase: 3
- Setting: Early breast cancer or DCIS after lumpectomy: accelerated partial-breast irradiation (twice daily over one week) versus whole-breast irradiation
- Sponsor: NRG Oncology (NSABP and RTOG)
- Enrolled: 4216
- Result: 10-year ipsilateral breast tumour recurrence 4.6% (partial breast) vs 3.9% (whole breast); equivalence not established.
- Outcomes: Ipsilateral breast tumour recurrence at 10 years: Accelerated partial-breast irradiation 4.6% vs Whole-breast irradiation 3.9%

## Sources

- ClinicalTrials.gov NCT00103181: https://clinicaltrials.gov/study/NCT00103181
- Lancet 2019: https://doi.org/10.1016/S0140-6736(19)32514-0

## Connected records

- cancers: [Ductal carcinoma in situ (DCIS)](https://onco.cc/cancers/ductal-carcinoma-in-situ/), [HER2-positive breast cancer](https://onco.cc/cancers/breast-her2-positive/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [High-dose-rate brachytherapy](https://onco.cc/technologies/hdr-brachytherapy/), [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/)

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