Abstract Background The EDIFICE surveys have been conducted every three years since 2005. The aim of the surveys is to provide a better understanding of the participation of the French population in cancer screening programs. The breast cancer screening program is nowadays widely implemented throughout the female population aged 50-74 years; however, the question of whether it could be adapted according to breast cancer risk factors is currently under debate. This analysis focuses on awareness of the nature of breast cancer risk factors among the lay population and physicians. Methods This fourth nationwide observational survey, EDIFICE 4, was conducted by phone interviews using the quota method. A representative sample of 1602 individuals aged between 40 and 75 years old was interviewed between June 12 and July 10, 2014. A mirror survey on a representative sample of 201 general practitioners (adjusted for age and geographical area) and 100 oncologists (adjusted for type of healthcare institution and geographical area) was conducted between July 9 and August 8, 2014. Interviewees were all asked to cite five main risk factors for breast cancer. Results For lay persons (737 women with no history of cancer), the breast cancer risk factors reported were: for 54%, heredity and family history; for 29%, unhealthy lifestyle, including smoking, poor diet, stress, alcohol, physical inactivity; for 15%, exposure to exogenous hormone therapy; for 4%, air pollution; for 4%, sunburn on breasts; for 4%, late childbearing or no childbearing, and for 2%, overweight/obesity. Among physicians (70 female general practitioners and 35 female oncologists), the breast cancer risk factors reported were: for 98%, heredity and family history; for 51%, exposure to exogenous hormone therapy; for 39%, late childbearing or no childbearing; for 32%, unhealthy lifestyle, including smoking, poor diet, stress, alcohol, physical inactivity; for 22%, overweight/obesity; for 20%, age; for 22%, no breast feeding, and for 2%, air pollution. Conclusion We observed a relatively satisfactory level of understanding regarding the different risk factors for breast cancer despite the lack of indication of any qualitative ranking. Although overweight is a known risk factor for breast cancer, this fact is still not clearly understood among physicians and not widely known by the general public. On the other hand, both physicians and also half of the lay population were well aware of the fact that heredity is a risk factor for breast cancer. Citation Format: Morère J-F, Viguier J, Blay J-Y, Touboul C, Lhomel C, Eisinger F, Pivot X. Awareness of brest cancer risk factors among lay persons and physicians. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-09-14.