The Absolute Effect / Evidence / Breast Cancer
START-B
Clinical question: After breast surgery, does 40 Gy in 15 fractions provide long-term local control and late effects comparable to 50 Gy in 25 fractions?
Registry / identifier: ISRCTN59368779 · One underlying study; aliases and follow-up publications consolidated.
Design, population and eligibility
UK multicentre randomized trial comparing conventional and hypofractionated whole-breast radiotherapy after surgery.
2,215 women: 1,105 assigned 50 Gy/25 fractions and 1,110 assigned 40 Gy/15 fractions.
Women with early breast cancer pT1–3a pN0–1 M0 after primary surgery; immediate reconstruction was excluded.
Median follow-up 9.9 years; 10-year locoregional relapse and late normal-tissue outcomes reported.
Treatment and comparator
Intervention: 40 Gy in 15 fractions of 2.67 Gy over 3 weeks.
Comparator: 50 Gy in 25 fractions of 2 Gy over 5 weeks.
Primary endpoint: Local-regional tumour relapse and late normal-tissue effects.
Key efficacy outcomes
10-year locoregional relapse: 4.3% with 40 Gy/15 vs 5.5% with 50 Gy/25 HR 0.77 (95% CI 0.51–1.16); p=0.21.
Late effects: Less breast shrinkage, telangiectasia and oedema with 40 Gy/15 Reported in long-term follow-up.
Absolute outcome visualization
Ten-year locoregional relapse, reported as cumulative incidence.
Bars show the source-reported endpoint values; they are not adjusted or reconstructed from median survival. For single-arm studies, no comparative effect is implied.
NNT / NNH and absolute benefit–harm balance
No NNT is presented: the observed recurrence difference was not statistically significant and the trial's primary inference is long-term comparative effectiveness, not superiority.
No NNH is calculated. Late breast effects were less frequent with 40 Gy/15, but the page does not invent absolute rates where the primary summary does not provide them.
Toxicity, grade 3–5 harms and treatment burden
Long-term assessments found significantly less breast shrinkage, telangiectasia and breast oedema with 40 Gy/15. The source abstract does not provide grade 3–5 toxicity rates; these are not inferred.
15 fractions over 3 weeks rather than 25 fractions over 5 weeks: ten fewer treatment visits and a shorter course. No concurrent chemotherapy was part of the radiotherapy comparison.
Quality of life and patient-reported outcomes
The START programme assessed quality of life; the ten-year report emphasizes late normal-tissue effects. A distinct long-term QoL advantage is not claimed here.
Subgroups and applicability
The trial included pT1–3a pN0–1 M0 disease. It is foundational for moderate hypofractionation; individual decisions still depend on anatomy, reconstruction, nodal targets and contemporary planning.
Critical appraisal and limitations
The trial compared two fractionation schedules in a historical treatment era. No superiority was demonstrated; absence of a significant difference is not proof of equivalence or non-inferiority.
Clinical interpretation
40 Gy in 15 fractions is a landmark moderate-hypofractionation regimen with durable local control and a favourable late-effect profile. Its practical advantage is reduced treatment burden; do not overstate the p=0.21 result as a formal NI test.
Contemporary-practice note (8 November 2026): This page separates the historical randomized or prospective study result from current treatment selection. A full guideline-level freshness review has not been completed for this batch; local decisions should be checked against current disease-specific guidance and multidisciplinary context.
Primary sources and related publications
- Haviland et al. Lancet Oncology 2013; 10-year START-A/B follow-up (PMID 24055415)
- START-B original randomized report
- ISRCTN59368779
All numerical claims above are linked to the primary publication or explicitly identified follow-up / meeting abstract. Missing data are not imputed.