Body Size And Breast Cancer Survival In The E3N Cohort Study

Mathilde HIS, INSERM,Paris-Saclay University, Paris-Sud Univ, UVSQ - Gustave Roussy, France
FAGHERAZZI G. 1,2 , MESRINE S. 1,2 , BOUTRON-RUAULT M. 1,2 , CLAVEL-CHAPELON F. 1,2 , DOSSUS L. 3

1 Paris-Saclay University, Paris-Sud Univ, UVSQ, CESP Generations and Health Team, INSERM, Villejuif, France
2 Gustave Roussy, Villejuif, France
3 Nutrition and Metabolism Section, International Agency for Research on Cancer, Lyon, France

Purpose
Obesity has been associated with poor breast cancer prognosis, but most studies focused on body mass index (BMI) and few considered different types of adiposity or changes in body size. Thus, we investigated associations between pre-diagnostic adiposity and breast cancer survival, considering BMI, waist and hip circumferences (WC and HC),  waist-to-hip ratio (WHR), as well as associations between changes in body size before and around diagnosis, and breast cancer survival.

Methods
Analyses included ~3,000 women from the French E3N prospective cohort study diagnosed with primary invasive breast cancer between 1995 and 2008. We investigated overall, breast cancer-specific and disease-free survival, overall and according to stage, menopausal and hormonal status and year of diagnosis, using Cox proportional hazard models adjusted for tumor characteristics and lifestyle risk factors.

Results
When compared to women with a pre-diagnostic HC<95cm, those with a HC>100 cm were at increased risk of death from all causes (Hazard Ratio (HR)>100vs<95cm=1.46, 95% Confidence Interval (CI)=0.99-2.15,Ptrend=0.04) and from breast cancer (HR>100vs<95cm=1.63, CI=1.02-2.61, Ptrend=0.03), and of second invasive cancer event ( HR>100vs<95cm=1.43, CI=1.10-1.84, Ptrend=0.006). Associations were stronger after adjustment for BMI. BMI, WC and WHR were not associated with survival after breast cancer. Analyses on changes in body size are ongoing and will be presented at the conference.
Conclusions
Our study underlines the interest of going beyond BMI when studying the association between adiposity and breast cancer survival. Further studies should be conducted to confirm our findings of an association between events after BC and hip circumference.

Funding source
This work was supported by the Fondation de France. Mathilde His was supported by a PhD fellowship from the French League against Cancer. The E3N study receives financial support from the French League against Cancer, the Mutuelle Générale de l'Education Nationale, Gustave-Roussy, and the National Institute of Health and Medical Research.