Glioblastoma (GBM) · Glioblastomas (also called GBM) are malignant Grade IV tumors, where a large portion of tumor cells are reproducing and dividing at any ...SkiptocontentGlioblastoma(GBM)Glioblastoma(GBM)Glioblastomas (alsocalledGBM) aremalignant GradeIVtumors,wherea large portion oftumorcellsarereproducing anddividing atanygiventime.Theyarenourishedbyanample andabnormaltumorvessel bloodsupply. Thetumorispredominantlymadeupofabnormal astrocyticcells,butalsocontainamixofdifferentcelltypes(includingbloodvessels)andareasof deadcells (necrosis).Glioblastomas areinfiltrativeandinvade into nearbyregions ofthebrain.Theycanalsosometimes spreadto theoppositesideofthebrainthroughconnectionfibers(corpuscallosum). Itisexceedinglyrarefor glioblastomas to spreadoutsideofthebrain. Glioblastomasmayarise denovo,meaningtheybeginasaGradeIVtumorwithnoevidenceofalowergradeprecursor. Denovo tumorsarethemostcommonformofglioblastomaandtendtobemoreaggressive and tendto affect olderpatients.Alternatively, secondaryglioblastomas mayprogressfromalower-grade astrocytictumors(GradeIIorGradeIII) andevolveintoGradeIVtumorsovertime. Ingeneral,thesetumorstendtobeslowergrowing initially,butcan progressively becomeaggressive. Glioblastomasareusuallydiagnosedaseither IDH-wildtype or IDH-mutant (pleaseseetheGeneticProfilesection belowformoreinformation).IDH-wildtypeglioblastomasaremorecommon,tendtobemoreaggressive,andhaveworseprognosisthanIDH-mutantglioblastomas. Location:Glioblastomasaregenerallyfoundinthecerebralhemispheresofthebrain,butcanbefoundanywhereinthebrain. IDHmutantglioblastomas tendto arisepreferentiallyinthefrontallobeSymptoms:Patientswithglioblastomasdevelop symptoms rapidly duetomasseffect fromthetumor itself or fromthe fluid surroundingthetumor(edema) thatcausesfurther brainswelling.Forexample,common symptoms atdiagnosis are relatedtotheincreasedpressureinthebrain (nausea,vomiting,andsevereheadaches whicharetypicallyworseinthemorning). Patientscanalsopresentwith neurological symptoms