Lifestyle Intervention Study in Adjuvant Treatment of Early Breast Cancer

The primary objective of this trial is to evaluate the effect of the addition of a 2 year, centrally delivered individualized, telephone-based lifestyle intervention focusing on weight management to a mailed educational intervention on Disease Free Survival in post-menopausal women with early stage breast cancer (hormone receptor positive), BMI ≥24-\<40 kg/m2, who are receiving standard letrozole adjuvant therapy. The telephone intervention will involve 19 phone calls, as well as mailings and a participant manual; women will be asked to lose up to 10% of their weight by reducing their caloric and fat intake (by 500-1000 kcal/day, 20% calories fat) and increasing their moderate physical activity (to 150-200 minutes/week). Secondary outcomes include overall survival, distant disease-free survival, weight change, health-related quality of life (HRQOL), selected non-cancer medical events and biologic factors (notably insulin). Approximately 2,150 women will be enrolled; follow-up will continue until target event rates have been met (anticipated 4-6 years after completion of the intervention). This sample size will provide 80% power (type 1 error 0.05 2-tailed) to detect a hazard ratio (HR) for DFS of 0.74-0.76 in the weight loss intervention arm.