课题CCO皮肤癌筛选.docx

课题CCO皮肤癌筛选.docx

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课题CCO皮肤癌筛选

2007CCO皮肤癌筛选

thantothepotentialharms（；Community-basedScreening；Aitkenetalinitiatedalarg；Attheendofthethree-yeari；Resultsfromcross-section；Thetrialcompletedatotalo；ScreeningbyPrimaryCarePr；There

thantothepotentialharms（e.g.,misdiagnosisofmelanomaorincreasedratesofbiopsyorotherproceduresforbenignskinconditions）.

Community-basedScreeningPrograms

Aitkenetalinitiatedalargerandomizedtrialtodeterminetheeffectivenessofcommunity-basedscreeninginreducingmortalityfrommelanomainAustralia（7）.In2002,resultsfromthefirstphaseofthetrialdemonstratedthefeasibilityofimplementingtheprogram,whichconsistedofcommunityeducation,generalpractitionereducation,andscreeningclinicstopromoteself-screeningandwhole-bodyscreeningbygeneralpractitioners.Earlyresultsdetectedanincreaseinthepercentageofsubjectsreportingwhole-bodyskinexaminationbyaphysician12monthsafterrandomizationcomparedtocontrolcommunities（27%versus[vs]12%;11%inbothgroupsreportedreceivinganexamintheyearbeforethestudy）.Theimpactofscreeningonmortalitywillrequirefollow-upofthosecommunitiesover15years,althoughthelackofadequatefundinghasjeopardizedthecompletionofthetrialasplanned.

Attheendofthethree-yearinterventionperiod（1998-2001）,atelephonesurveyofasampleofpeopleinthestudycommunitiesindicatedthatpeoplecouldaccuratelyrecallwhethertheyhadhadaclinicalwhole-bodyskinexaminthepreviousthreeyears.Concordanceofself-andmedicalrecordreportswas94%,withsensitivity92%andspecificity96%（22）.

Resultsfromcross-sectionalsurveys（telephoneandpostal）thatwereconductedininterventionandcontrolcommunitiesatbaseline,duringthe3yearinterventionand2yearsaftertheinterventionshowedanincreased12monthprevalenceofwholebodyskinexams2yearsintotheinterventionperiod（from11.2percentto34.8）intheinterventionarm.Howeverthisdeclinedinthethirdyearto29.2（whenclinicswerediscontinued）anddroppedafurther10percent2yearsaftertheprogramended.Incomparison,controlcommunitieshadstablescreeningratesoverthesametimeperiods.Theauthorsnotethatwithouttheprovisionofdedicatedskinscreeningclinicsitwouldnotbepossibletomaintainhighscreeninglevels（24）.

Thetrialcompletedatotalof16,383screensoverthreeyearsand2302referralsweremadeforsuspiciouslesions（14percent）.Atotalof33melanomas,259BCCs,and97SCCswereconfirmedfromthe16383screensforanoverallprobabilityofdetectingskincancerof2.4percent（25）.

ScreeningbyPrimaryCareProviders

Therewerenocomparativestudiesofscreeningbyprimarycareproviders,butanon-comparativeprospectivestudyevaluatedscreeningforskincancerintheprimarycaresetting

（26）.ThegeneralizabilityofresultsfromthatItalianstudyislimitedbylowparticipationrates.

Veronesietalinvited1,038generalpractitionersinItalytoparticipateinaskincancer-screeningprogram（26）.Theywereaskedtoscreenalladultspresentingtotheirofficesforanyreasonoveratwo-yearperiod.Aregionalprogramprovidededucationforpractitionersandproceduresforreferraltospecialists.Among74participatingpractices,11,040patientshadaskinexaminationand820werereferredtodermatologists.Thestudyreportdidnotprovidedetailsaboutthepatientpopulation.Theyieldfromscreeningwas38melanomas（0.3%ofpatientsscreened）and94non-melanomaskincarcinomas（0.9%）.Thepurposeofthescreeningprogramwastheearlydiagnosisofcutaneousmelanoma,andlittleinformationisreportedaboutthenon-melanomaskincancersdetected.

SkinSelf-Examination

Datafromthreestudiesaresummarizedbelow.Acase-controlstudyexaminedtheimpactofskinself-examination（SSE）onmelanomadetectionandmortality（9）.TheothertwostudiesprovidedinformationabouttheimpactofskinexaminationbyaphysicianonsubsequentSSE（8,23）.

Berwicketalusedacase-controlstudyofmelanomatoinvestigatewhetherSSEwasbeneficial（9）.ThestudyassessedthepotentialofSSEforprimarypreventionofmelanoma（i.e.,reductionofmelanomarisk）andsecondaryprevention（earlydetection）separately,aswellasthejointimpactonmelanomamortalityreduction.Interviewswereconductedwith650individualswithmelanomasdiagnosedin1987-1989,identifiedfromtheConnecticutTumorRegistry,and549populationcontrols,selectedfromtheConnecticutpopulationbyrandom-digitdialling.AllsubjectswereCaucasian.Participantswereaskedabouttheirhistoryofdoing―careful,deliberateandpurposefulskinselfexamination‖priortodiagnosis/interview;17%ofcontrols（n=96）and13%（n=86）ofcasesrepliedaffirmatively.Melanomacaseswerefollowedthrough1994fordevelopmentof―lethalmelanoma‖;30developeddistantmetastasesbutwerestillalive,and80diedfrommelanoma.

ThecomparisonoftheuseofSSEincasesandcontrolsindicatedareducedriskofmelanomaassociatedwithSSEforprimaryprevention,withanoddsratio（OR）of0.66（95%confidenceinterval[CI],0.44to0.99）afteranadjustmentforage,sex,andanumberofphenotypicriskfactorsandestimatedsunexposure.Intermsofsecondaryprevention,SSEwasassociatedwithareducedriskofdeveloping―lethalmelanoma‖（OR,0.56）.ThecombinedprimaryandsecondarypreventioneffectsofSSErepresentanestimateofthepotentialforSSEtoreducemelanomamortality,theusualdesirableendpointforevaluatingscreeningeffectiveness.TheadjustedORrepresentingthisreductionis0.37（95%CI,0.16to0.84）,whichisalsotheproductofprimaryandsecondarypreventionORs（i.e.,0.66x0.56=0.37）.

Therearesomemethodologicalproblemswiththisapproachtotheassessmentofscreeningeffectiveness.Themostseriouschallengetothevalidityoftheestimaterelatingtosecondaryprevention,andthereforetothecombinedeffect,isthepossibilityoflead-timebias（i.e.,thatthosedoingSSEfindtheirlesionsearlierandsosurvivelongerfromthetimeofdiagnosistodeathbutdonotnecessarilylivetoanolderagethantheywouldhaveintheabsenceofSSE）.Thestudyauthorsarguedthatlead-timebiasisunlikelytobeamajorissuebecause,bytheendoffollow-up,thenumberofnew―lethalmelanomas‖hadreachedaplateauinboththeSSEandnon-SSEgroups.

Azizietalconductedanon-randomizedprospectivetrialofinterventionstoimproveskincancerawarenessandpreventionamongoutdoorworkersinIsrael（8）.Thecontrolandinterventionsubjectscamefromdifferentworksitesbutworkedforthesamecompany.Abaselineevaluationfoundthat44%ofworkersreportedperformingSSEatleastonceayear.Eightmonthsaftertheintroductionofaneducationandscreeningprogram,threequartersoftheinterventionsubjectsreportedperformingSSE,comparedtohalfofthecontrolgroup.

IntheAustralianrandomizedtrialofcommunity-basedscreeningnotedabove,AitkenetalfoundthatoneofthemostimportantdeterminantsofconductingSSEwashavinghadaskinexaminationbyaphysicianwithinthepastthreeyears（23）.AlmostasimportantwashavinghadaphysiciansuggestdoingSSEorgivinginstructiononhowtoperformSSE.

RiskFactorsforSkinCancer

Itiswellacceptedthatsomeindividualsareatanincreasedriskforskincancerbecauseofpersonalcharacteristicsorhistory.Althoughtheevidenceonthebenefitsofscreeningisverysparse,theguidelinepanelproposedthatanybenefitexpectedfromincreasedsurveillanceforskincancerwouldhavethebiggestimpactinhigh-riskgroups.

Therearefivecategoriesofdefinedriskfactorsforskincancer:

1.phenotypiccharacteristics,

2.exposuretoultravioletradiationfromeitherthesunorartificialtanningdevices,

3.genemutations,familyorpersonalhistoryofskincancer,andinheritedconditionssuch

asatypicalneviordysplasticnevussyndrome,

4.medicalconditionsortreatments,

5.dysplasticneviwithoutafamilyhistory.

Personalriskofskincancerdependsonboththerelativerisk（RR）associatedwitheachfactorandthenumberofriskfactors.Riskisassumedtobemultiplicative,sothatoverallriskcanbeestimatedfromtheproductsoftherelativeriskassociatedwitheachfactorpresentinanindividual（27）.

Phenotype

Peoplewithnaturallyblondorredhair,withatendencytofreckle,andwhoseskinburnseasilyandtanspoorlyornotatall（skintypeI）haveanincreasedsusceptibilityforallformsofskincancer（28）.Thosewithlightskincolouralsohaveahigherthanaveragerisk.Skincolouriscorrelatedwithhaircolour,andeitheroneortheothercapturesthetraitof―fairness,‖buthaircolouriseasiertoassess.Additionally,thosewithmanyneviareatincreasedriskforallmelanomavariants（29）.Thetablesbelowfurthersummarizetheseriskfactors.Table1providesdataontheassociationsofskincolour,tanningability,freckling,andneviwiththethreetypesofskincancerinanAustralianpopulation（30）,whileTable2includesasimilarsetofcharacteristicsfromacase-controlstudyofmelanomaconductedinsouthernOntariointhe1980s（27）.Thesecomprisethesetofphenotypicfactorsthatwerejointlysignificantlyassociatedwithincreasedriskofmelanoma.

Multiplenevirepresentanindicatorofbothexposureandsusceptibility.Neviariseinchildhoodandadolescenceinresponsetosunexposure.Somepeoplegetmanyneviandothersnoneorfewforthesameamountofsunexposure.Arecentmeta-analysisfoundthattherelativeriskofmelanomawas1.019foreachadditionalnevuswhenwhole-bodycountswereused（31）.Thus,peoplewith101-120neviwouldhavearelativeriskof6.89（95%CI:

4.63-10.25）comparedtotho