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BWEL is a trial of more than 3,000 women testing whether losing weight after breast cancer treatment reduces recurrence. The programme achieved weight loss; the effect on recurrence was not clearly shown at the first analysis.
BWEL randomised 3,181 women within 12 months of diagnosis to a two-year telephone-delivered lifestyle programme (calorie restriction, 150-225 minutes of moderate activity per week, 42 coaching calls) plus health education, or health education alone; the primary endpoint was invasive disease-free survival. The intervention produced significantly greater weight loss at 12 and 24 months than the control arm. Primary efficacy results were presented in late 2025 and reported as not demonstrating a statistically significant improvement in invasive disease-free survival at the planned analysis; full peer-reviewed publication and longer follow-up are awaited, and the effect sizes below should be checked against the publication when available. Interpretation is contested: the weight loss achieved was modest (a few percent of body weight), follow-up is relatively short for HR-positive disease, and secondary cardiometabolic and quality-of-life benefits were seen. BWEL is the largest lifestyle-intervention trial ever run in cancer survivors and its design (telephone coaching, scalable) remains the template.
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.
3,181 enrolled.
Event-driven primary analysis not yet published; ClinicalTrials.gov lists primary completion in 2030. Only weight and quality-of-life secondary analyses have been reported (2025-2026).
SourceMean -4.3 kg vs +0.9 kg; 3,180 women analysed
Source| Endpoint | Arm | n | Value | HR (95% CI) | p | Source |
|---|---|---|---|---|---|---|
| Invasive disease-free survivalprimary | Telephone weight-loss intervention + health education | - | Event-driven primary analysis not yet published; ClinicalTrials.gov lists primary completion in 2030. Only weight and quality-of-life secondary analyses have been reported (2025-2026). | - | - | link |
| Health education alone | - | - | ||||
| Weight change from baseline at 1 year | Telephone weight-loss intervention + health education | 1,591 | -4.7% | - | <0.001 | link |
| Health education alone | 1,589 | 1% |
Shares Energy balance, Dietitian-led weight-loss programmes in HR-positive breast cancer, Diet, exercise and lifestyle roadmap: causes established → interventions that disappointed → exercise proven as treatment, Failures are hidden.
Shares GLP-1 receptor agonists as adjuvant weight-loss therapy in HR-positive breast cancer, Energy balance, Dietitian-led weight-loss programmes in HR-positive breast cancer, Obesity-related cancers (IARC list of 13).
Shares Decentralised trial, Energy balance, Pragmatic trial, Event-free / disease-free survival (EFS, DFS, iDFS, RFS).
Shares Energy balance, Diet, exercise and lifestyle roadmap: causes established → interventions that disappointed → exercise proven as treatment, Exercise & lifestyle oncology, Survivorship and late effects are neglected.
Shares Energy balance, Dietitian-led weight-loss programmes in HR-positive breast cancer, Obesity-related cancers (IARC list of 13), Diet, exercise and lifestyle roadmap: causes established → interventions that disappointed → exercise proven as treatment.
Shares Decentralised trial, Pragmatic trial, Event-free / disease-free survival (EFS, DFS, iDFS, RFS).
Shares Energy balance, Dietitian-led weight-loss programmes in HR-positive breast cancer, Obesity-related cancers (IARC list of 13), Exercise & lifestyle oncology.
Shares Energy balance, Obesity-related cancers (IARC list of 13), Diet, exercise and lifestyle roadmap: causes established → interventions that disappointed → exercise proven as treatment.