Theriskofbreastcancer(BC)overdiagnosisattributedtomammographyscreeningisanunresolvedissue,complicatedbyheterogeneityinthemethodologyofquantifyingitsmagnitude,andbothpoliticalandscientificelementssurroundinginterpretationoftheevidenceonthisphenomenon.EvidencefromrandomizedtrialsandalsofromobservationalstudiesshowsthatmammographyscreeningreducestheriskofBCdeath;similarly,thesestudiesprovidesufficientevidencethatoverdiagnosisrepresentsaseriousharmfrompopulationbreastscreening.Forboththeseoutcomesofscreening,BCmortalityreductionandoverdiagnosis,estimatesofmagnitudevarybetweenstudieshoweveroverdiagnosisestimatesareassociatedwithsubstantialuncertainty.Thetrade-offbetweenthebenefitandthecollectiveharmsofBCscreening,includingfalse-positivesandoverdiagnosis,ismorefinelybalancedthaninitiallyrecognized,howeverthesnapshotofevidencepresentedonoverdiagnosisdoesnotmeanthatbreastscreeningisworthless.Futureeffortsshouldbedirectedtowards(a)ensuringthatanychangesintheimplementationofBCscreeningoptimizethebalancebetweenbenefitandharms,includingassessinghowplannedoractualchangesmodifytheriskofoverdiagnosis;(b)informingwomenofalltheoutcomesthatmayaffectthemwhentheyparticipateinscreeningusingwell-craftedandbalancedinformation;and(c)investinginresearchthatwillhelpdefineandreducetheensuingovertreatmentofscreen-detectedBC.
