Abstract ES8-1: Windows of susceptibility across the lifecourse and breast cancer

Abstract

Abstract With increasing knowledge regarding the role of various factors in the development of breast cancer, a concept that has attracted substantial attention is that of windows of susceptibility. This concept suggests that there are periods over the lifecourse during which a woman may be particularly vulnerable to the influence of modifiable factors in determining long-term risk of breast cancer. This concept is not new; for example, among atomic bomb survivors in Japan, it has been observed that the effect of radiation exposure on subsequent breast cancer risk is substantially higher if women were exposed earlier in life than in their later years. However, the impact of hormonally-active agents that are ubiquitous in environment has raised concern that the risk of breast cancer may be altered during windows of susceptibility, such as during the in utero period, the pubertal transition, or between puberty and first full-term pregnancy. In order to better understand the interplay of environmental and lifestyle factors with timing of exposures during the lifecourse, the National Cancer Institute and the National Institute for Environmental Health Sciences established the Breast Cancer and the Environment Research Program, including both laboratory and epidemiologic studies to investigate the potential role of hormonally-active agents in altering early life factors that may influence breast cancer risk. These include, for example, epidemiologic studies that have focused on impacts on age-at-onset of puberty, and others that focus on impacts on breast density. In conjunction with other studies that have examined body size or other metabolic parameters measured at different periods over the lifecourse, a growing body of literature indicates that breast cancer risk factors may operate differently depending on when exposures to these risk factors occur. These observations indicate that establishment of breast cancer risk is complex, and that approaches to prevention likely need to recognize the importance of windows of susceptibility in influencing long-term likelihood of developing breast cancer. This presentation will review some of the key concepts and findings underlying this growing area of interest in the epidemiology of breast cancer. Citation Format: Kushi L. Windows of susceptibility across the lifecourse and breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr ES8-1.