Development and Spread of Cancer - MSD Manuals

The first step in cancer development is initiation, in which a change in a cell's genetic material (a mutation) primes the cell to become cancerous. MSDManual PleaseconfirmthatyouarenotlocatedinsidetheRussianFederation Yes No LeavethisSite? Thelinkyouhaveselectedwilltakeyoutoathird-partywebsite.Wedonotcontrolorhaveresponsibilityforthecontentofanythird-partysite. Continue Cancel honeypotlink HOME HEALTHTOPICS CommonHealthTopics BloodDisorders Bone,Joint,andMuscleDisorders Brain,SpinalCord,andNerveDisorders Cancer Children'sHealthIssues DigestiveDisorders DisordersofNutrition Drugs Ear,Nose,andThroatDisorders EyeDisorders Fundamentals HeartandBloodVesselDisorders HormonalandMetabolicDisorders ImmuneDisorders Infections InjuriesandPoisoning KidneyandUrinaryTractDisorders LiverandGallbladderDisorders LungandAirwayDisorders Men'sHealthIssues MentalHealthDisorders MouthandDentalDisorders OlderPeople’sHealthIssues SkinDisorders SpecialSubjects Women'sHealthIssues Resources Videos Figures Images Quizzes CommonMedicalTests ViewAllResources SYMPTOMS General ALLSYMPTOMS> EMERGENCIES CardiacArrest Choking ALLEMERGENCIES> RESOURCES Abbreviations Audio 3DModels CommonMedicalTests Figures FirstAid Images Infographics MedicalTerms TheOne-PageManualofHealth Pronunciations Quizzes Self-AssessmentTools Tables Videos Weights&Measures NEWS AddingTheseFoodstoYourDietCouldKeepDementiaAway AmericansNowLivingLongerAfterHeartAttack CancerinYouthMeansHeightenedOddsforAnotherCancerLater CouldStudentLoanDebtThreatenYourHealth? ViewAllNews> ABOUT Overview History EditorsandtheEditorialProcess PublishingandProductionStaff EditorialBoard Contributors Reviewers ContentProviders GlobalMedicalKnowledge FAQ ContactUs HealthTopics&Chapters A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Home / Cancer / OverviewofCancer / ... / DevelopmentandSpreadofCancer / INTHISTOPIC Initiation Promotion Spread OTHERTOPICSINTHISCHAPTER OverviewofCancer DevelopmentandSpreadofCancer RiskFactorsforCancer WarningSignsofCancer SymptomsofCancer ParaneoplasticSyndromes DefensesAgainstCancer DiagnosisofCancer ADDITIONALCONTENT Testyourknowledge Small-IntestineCancer Adenocarcinomaisthemostcommonsmall-intestinecancer.Adenocarcinomasdevelopintheglandularcellsoftheliningofthesmallintestine. Peoplewithwhichdisorderaremostlikelytodevelopadenocarcinoma?  Celiacdisease   Crohndisease    Duodenalulcer    Irritablebowelsyndrome MoreContent Videos News SOCIALMEDIA DevelopmentandSpreadofCancer By RobertPeterGale ,MD,PhD,ImperialCollegeLondon Lastfullreview/revisionSep2020|ContentlastmodifiedSep2020 CLICKHEREFORTHEPROFESSIONALVERSION GETTHEQUICKFACTS TopicResources 3DModels(0) Audios(0) Calculators(0) Images(0) LabTest(0) Tables(0) Videos(1) CancerCells Malignanttransformationisthecomplexprocessbywhichcancerouscellsdevelopfromhealthycells.Itconsistsofseveralsteps:InitiationPromotionSpread(SeealsoOverviewofCancerOverviewofCancerAcancerisanabnormalgrowthofcells(usuallyderivedfromasingleabnormalcell).Thecellshavelostnormalcontrolmechanismsandthusareabletomultiplycontinuously,invadenearby...readmore.)InitiationThefirststepincancerdevelopmentisinitiation,inwhichachangeinacell’sgeneticmaterial(amutation)primesthecelltobecomecancerous.Thechangeinthecell’sgeneticmaterialmayoccurspontaneouslyorbebroughtonbyanagentthatcausescancer(acarcinogen).CarcinogensSomeCarcinogensincludemanychemicals,tobacco,viruses,radiation,andsunlight.However,notallcellsareequallysusceptibletocarcinogens.Aninheritedoracquiredgeneticflawinacellmaymakeitmoresusceptible.Evenchronicphysicalirritationmaymakeacellmoresusceptibletocarcinogens.PromotionThesecondandfinalstepinthedevelopmentofcancerispromotion.Agentsthatcausepromotion,orpromoters,maybesubstancesintheenvironmentorevensomedrugssuchassexhormones(forexample,testosteronetakentoimprovesexdriveandenergyinoldermen).Unlikecarcinogens,promotersdonotcausecancerbythemselves.Instead,promotersallowacellthathasundergoneinitiationtobecomecancerous.Promotionhasnoeffectoncellsthathavenotundergoneinitiation.Somecarcinogensaresufficientlypowerfultobeabletocausecancerwithouttheneedforpromotion.Forexample,ionizingradiation(whichisusedinx-raysandisproducedinnuclearpowerplantsandatomicbombexplosions)cancausevariouscancers,particularlysarcomas,leukemia,thyroidcancer,andbreastcancer.SpreadCancercangrowdirectlyinto(invade)surroundingtissueorspreadtotissuesororgans,nearbyordistant.CancercanspreadthroughthelymphaticsystemOverviewoftheLymphaticSystemThelymphaticsystemisavitalpartoftheimmunesystem.Itincludesorganssuchasthethymus,bonemarrow,spleen,tonsils,appendix,andPeyerpatchesinthesmallintestinethatproduce...readmore.Thistypeofspreadistypicalofcarcinomas.Forexample,breastcancerusuallyspreadsfirsttothenearbylymphnodesinthearmpit,andonlylaterdoesitspreadtodistantsites.Cancercanalsospreadviathebloodstream.Thistypeofspreadistypicalofsarcomas. 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