title: The Million Women Study, an additional observational study with the implications and limits of an observational study.
authors.affiliation: Poliklinik für gynäkologische Endokrinologie und Reprodunktionsmedizin, Universitätsklinikum Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany. braendle@uke.uni-hamburg.de
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Braendle
mesh_terms: D001943:Breast Neoplasms / Q000139:chemically induced* / Q000453:epidemiology / Q000401:mortality; D015914:Estrogen Replacement Therapy / Q000009:adverse effects; D005260:Female; D006801:Humans; D019370:Observation; D016032:Randomized Controlled Trials as Topic; D012107:Research Design; D012307:Risk Factors