This study expands upon an existing case-control study we call the Women's Environment Cancer and Radiation Epidemiology (WECARE) Study. For simplicity, in this protocol, we will refer to that study as the "parent" study. The goal of both studies is to examine the interaction of radiation exposure and genetic susceptibility factors in the etiology of breast cancer. A subset of study participants who consented to 'future contact' in the GWA Study (and those in the 'parent' study from selected sites) will be included in an analysis of radiation-related heart disease and related conditions.