Weight Change and Survival after Breast Cancer in the After Breast Cancer Pooling Project
A partir des données de 4 études de cohortes prospectives menées en Chine et aux Etats-Unis incluant 12 915 participantes, cette étude analyse l'impact des variations de poids sur la survie des patientes atteintes d'un cancer du sein
Background: Weight change after a breast cancer diagnosis has been linked to lower survival. To further understand effects of post-diagnostic weight variation on survival, we examined the relationship by comorbid status and initial BMI. Methods: The current analysis included 12,915 breast cancer patients diagnosed between 1990 and 2006 with Stage I-III tumors from four prospective cohorts in the US and China. Hazard ratios (HR) and 95% confidence intervals (CI) representing the associations of five weight change categories (within <5% [reference]; 5-<10% and ≥10% loss and gain) with mortality were estimated using Cox proportional hazards models. Results: Mean weight change was 1.6kg. 14.7% of women lost and 34.7% gained weight. Weight stability in the early years post-diagnosis was associated with the lowest overall mortality risk. Weight loss ≥10% was related to a 40% increased risk of death (HR=1.41; 95% CI: 1.14, 1.75) in the US and over three times the risk of death (HR=3.25; 95% CI: 2.24, 4.73) in Shanghai. This association varied by pre-diagnosis BMI, and in the US lower survival were seen for women who lost weight and had comorbid conditions. Weight gain ≥10% was associated with a non-significant increased risk of death. Conclusions: Prevention of excessive weight gain is a valid public health goal for breast cancer survivors. Although intentionality of weight loss could not be determined, women with comorbid conditions may be particularly at risk of weight loss and mortality. Impact: Weight control strategies for breast cancer survivors should be personalized to the individual's medical history.