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Geneticprofleofcolorectalcancerlivermetastases
fewgeneslowerstheconcordancebelow90%(50–80)andfnallysequencingof1000
genesinaseparatecohortcausedconcordancefalltoonlyabout5%betweenprimary
tumourandmetastases.
Thelowerreportedconcordancecouldbeattributabletointra-tumourheterogeneity
andresistanceofmetastasestothecytotoxicandbiologictreatment.Itwasadditionally
shownthat,metastasespossessgreaternumberofmutationsthenprimarytumour.
Ontheotherhand,applyingsensitivemethodscouldimproveconcordance.Thecon-
cordancestronglydependsonadequatesampleusedfortestingaswell.Theliverme-
tastasescouldbeeasilybiopsiedtocollectenoughmaterialformoleculardiagnostics
comparingtowithmetastasestothelungwhicharemorechallengingtosample.
Inconclusionthereishighconcordanceacrosstestedbiomarkersbetweenprimarytu-
moursandtheirlivermetastases,especiallyincaseofmarkerswithpredictivevalue
(KRAS,NRAS,BRAF).Theaboveresultsuggeststhatmoleculartestingcouldbedoneby
usingoneofthetwoabove-mentionedlocalizations[32].
1.2.
DISAGGREGATION,INVASIONANDINTRAVASA-
TIONOFMALIGNANTCELLS
Dissociationordisaggregationistheprocess,inwhichtumourcellsacquirediverse
alterationsingeneexpressionandthereforecellularfunctions,suchasadecreasein
epithelialmarkers(E-cadherin)andanincreaseinmesenchymalmarkers(N-cadherin,
vimentin,fbronectinetc.),whichiscalledepithelialtomesenchymaltransition(EMT).
Moreover,inthisprocessthecancercell,expandmigratoryandinvasivecapacities
andthereforedetachesfromtheprimarytumourandinvadesurroundingtissues[34,
35,36].
Duringthisphase,cancercellsinteractwithneighbouringstromalcells(fbroblasts,
macrophages15,lymphocytes,neutrophils,endothelialcells,dendriticcells,platelets),
extracellularmatrix(ECM)components(collagen,elastin,laminin,etc.),leadingto:
(1)neoangiogenesis16,(2)activationandproliferationofcancerassociatedfbroblasts17
15M1macrophages(CD11b+,CD80+,CD86+,CD204+,CD284+,CD14+,CD68+)
presentanti-tumouractivity,whileM2macrophages(TAM:tumour-associatedmacrophages;CD23+,
CD169+,CD206+,CD163+,CD14+,CD68+)aretumourgrowthfavouringonce,andareresponsiblefor:
immunosuppression,inactivationofTlymphocytes,tumourangiogenesis,productionofproteolyticenzymes
remodellingextracellularmatrix,stimulatingtomormotilityandproductionofgrowthfactors.
16Neoangiogenesisisswitchedonwhenoxygendiffusionfromthenormalcapillarynetworkis
unabletosupplytumourlargerthan1-2mm,thisprocessisrelatedtothebalancebetweenproangiogenic
factors:VEGF(Vascularendothelialgrowthfactor),PDGR(Platelet-derivedgrowthfactor),FGF(Fibroblastgrowth
factor),angiopoietin,etc;andanti-angiogenicfactors:endostatin,angiostatin,andTSP(Thrombospondins),etc.
17Earlyintumourogenesisfbroblastsinhibitearlystagesoftumourprogression[13,14].
duringcancergrowth,asaresultofmechanicaltension,fbroblastsacquirethemiyofbroblastphenotyoe,
8