This study at Yale University in New Haven, CT, is investigating the effects of hormone replacement therapy and other types of estrogen exposure on a marker of breast cancer risk the research team has identified. The researchers originally wanted to enroll up to 1,500 volunteers. The Call to Action for this study was sent to Army of Women members on April 17, 2013. After the Army of Women members began responding in high numbers to the Call to Action, the research team decided to keep the study open and recruit as many women as possible in a one-month period. Doing so will allow the team to study a wide variety of survivors, including pre- and post-menopausal women and women with different stages and grades of breast cancer. When the study closed on May 22, 2013, the Army of Women had provided the team with more than 2,460 women who were interested in enrolling in the study.