Ettinger B, et al. – In an effort to assess the role of postmenopausal estrogen replacement therapy in the development of breast cancer, researchers examined the incidence of breast cancer in women who had taken long-term estrogen (average 17.2 years) vs women who had not taken estrogen. In this long-term, retrospective cohort study, they analyzed 454 women born 1900-1915 who were members of a large health maintenance organization in northern California. By the end of 1995, they found that breast cancer had developed in 26 (11.2%) of estrogen users vs 9 (4.1%) among the nonusers. Findings indicated a substantially increased risk of breast cancer in correlation to long-term estrogen use.