AdenofibromaPhyllodes TumorBreast DiseasesBreast NeoplasmsUltrasonography, MammaryBreastEthinyl Estradiol-Norgestrel CombinationApocrine GlandsBreast CystChoristomaBiopsy, NeedleCarcinoma, Ductal, BreastEstriolMammographyToxicity Tests, ChronicSclerosisCarcinogenicity TestsNeoplasms, Multiple PrimaryCarcinoma, Intraductal, NoninfiltratingPapillomaMetaplasiaBiopsyCarcinoma, LobularHyperplasiaCarcinoma in SituDiagnostic ErrorsFibroadenomaBiopsy, Fine-NeedleRats, Inbred F344CarcinomaNeoplasms, ExperimentalImmunohistochemistryRetrospective StudiesCase-Control StudiesAge FactorsFollow-Up Studies