The Absolute Effect / Evidence / EORTC 22881/10882 (Boost versus No Boost)
EORTC 22881/10882 (Boost versus No Boost)
After complete lumpectomy and whole-breast irradiation for early breast cancer, does a 16 Gy tumour-bed boost improve long-term local control, and what is the fibrosis trade-off?
Registry: NCT02295033 · One underlying randomized study; aliases and follow-up reports consolidated.
Design, population and eligibility
EORTC phase III randomized trial within breast-conserving therapy; 5,569 randomized overall.
5,318 patients after microscopically complete lumpectomy randomized to no boost or 16 Gy boost; 251 incompletely excised cases were separately randomized between boost doses.
Early breast cancer treated with lumpectomy and whole-breast irradiation; analysis of the complete-excision cohort is the relevant 0 Gy versus 16 Gy comparison.
Long-term follow-up to 20 years for local recurrence and late toxicity.
Treatment and comparator
Whole-breast irradiation 50 Gy in 25 fractions followed by a 16 Gy tumour-bed boost (8 fractions of 2 Gy).
Whole-breast irradiation 50 Gy in 25 fractions without a tumour-bed boost.
Primary endpoint: Local recurrence after breast-conserving treatment.
Other endpoints: OS, fibrosis, cosmesis and age-related local control.
Key efficacy results
At 20 years, cumulative ipsilateral breast tumour recurrence was 12.0% with boost versus 16.4% without boost; HR 0.65 (99% CI 0.52–0.81), P<0.0001.
At 20 years, severe fibrosis was 5.2% with boost versus 1.8% without boost.
Twenty-year OS was 59.7% with boost versus 61.1% without boost; HR 1.05 (99% CI 0.92–1.19), P=0.323. The boost primarily improves local control, not survival.
The 10-year report showed local recurrence 6.2% with 16 Gy versus 10.2% without boost; severe fibrosis at 10 years 4.4% versus 1.6%.
Source-reported outcome visualization
Twenty-year freedom from local recurrence · 20 years
Complements of cumulative local recurrence reported in the long-term analysis.
Absolute effect
Absolute 20-year local recurrence reduction was 4.4 percentage points (16.4% to 12.0%); approximate NNT = 23 over 20 years. Severe fibrosis increased by 3.4 percentage points (1.8% to 5.2%); approximate NNH = 29 over 20 years. Both are fixed-horizon estimates from the same randomized cohort.
NNT: Approximately 23 at 20 years to prevent one local recurrence.
NNH: Approximately 29 at 20 years for one additional case of severe fibrosis.
Toxicity, harms and treatment burden
Severe fibrosis at 20 years: 5.2% with boost versus 1.8% without boost; absolute increase 3.4 points.
The boost adds 16 Gy in eight fractions, increasing treatment visits and acute/late tissue burden.
Grade 3–5 systemic toxicity and treatment discontinuation are not applicable as systemic treatment endpoints; the relevant late harm is breast fibrosis and cosmetic change.
Quality of life and patient-reported outcomes
The boost may reduce local recurrence but increases fibrosis and can affect breast appearance, firmness and patient satisfaction. The trial's primary evidence supports a local-control trade-off rather than a survival or global QoL gain.
Subgroups, maturity and limitations
The absolute benefit is larger in younger patients with higher baseline recurrence risk; the boost decision should be risk-adapted rather than automatic.
The complete-excision 5,318-patient cohort is distinct from the 251 patients with microscopically incomplete excision who were randomized to different boost doses.
Twenty-year results are mature; the late toxicity trade-off becomes more visible with long follow-up.
Clinical interpretation
Current-practice context · 1 November 2026 (full guideline freshness review pending): Use contemporary risk-adapted boost indications considering age, grade, margins, biology and expected life span. Modern hypofractionation and boost schedules differ from the historical regimen, so avoid assuming identical toxicity rates.
Primary sources and registry
- Bartelink et al. Lancet Oncology 2015 (20-year follow-up)
- Poortmans et al. Cancer Radiotherapy 2008 (10-year results)
- EORTC trial record
Source hierarchy: primary randomized report and prespecified follow-up first. Missing numerical toxicity, discontinuation or QoL data are labelled rather than imputed.