Neoplasm Regression, SpontaneousMammary Glands, AnimalRegression AnalysisLactationThymus GlandPancreatic NeoplasmsNeoplasmsPostpartum PeriodPregnancyNeoplasms, Cystic, Mucinous, and SerousEpithelial CellsHemangiomaLogistic ModelsSkin NeoplasmsClusterinRisk FactorsImmunohistochemistryApoptosisMilk ProteinsNeoplasms, Multiple PrimaryTime FactorsAgingKidney NeoplasmsNeoplasms, Second PrimaryOrgan SizeBreastRetrospective StudiesLung NeoplasmsBreast NeoplasmsWeaningAdenocarcinoma, MucinousLinear ModelsThyroid NeoplasmsMice, TransgenicUterusAtrophyCohort StudiesPregnancy, AnimalCaseinsMyeloproliferative DisordersEndometritisAge FactorsLiver Neoplasms