Dietitian-led weight-loss programmes in HR-positive breast cancer

Obesity at diagnosis is associated with roughly 30% higher breast cancer mortality in meta-analyses, and with reduced aromatase inhibitor efficacy, making intentional weight loss an attractive adjuvant strategy. The Breast Cancer Weight Loss (BWEL, Alliance A011401) trial randomised 3,181 women with stage II-III HR-positive or HER2-positive breast cancer and BMI at least 27 to a two-year telephone-based lifestyle intervention (calorie restriction, 150-225 minutes of activity a week, health coaching) plus health education, or health education alone, with invasive disease-free survival as the primary endpoint. The intervention produced clinically meaningful weight loss at one and two years; primary results presented in late 2025 were reported as not showing a statistically significant iDFS improvement at the primary analysis, with longer follow-up and subgroup analyses to come (see trial record for caveats). Whether that reflects insufficient weight loss, too short a follow-up, or a true absence of effect is now the central question, and pharmacological weight loss with GLP-1 receptor agonists is the obvious next test. Weight-loss programmes remain justified for cardiometabolic health, fitness and quality of life in survivors.