“…In contrast to obstructive uropathy causedbystones,thebiologicalgenesisinprostatecanceris extrinsic, caused by external compression of ureter or bladder,orindirectlybyelevationofthetrigone.Whileastentin patients suffering from urolithiasis simply facilitates passage of the concrements, it needs to resist external compression andinvasioninthecaseofmalignantcompression.Thus,even ifastentisabletobypasstheinternalureteralnarrowing,it willlikelyfailovertime [15].Thismightexplainlowersuccess ratesforstentingofextrinsicobstructionasopposedtointrinsicocclusion [16,17].Thedifferentsortsofreportedstentsdid not allow a systematic assessment of the impact of different stent materials on the outcome in prostate cancer patients. Atpresent,polyurethaneandsiliconearethemostfrequently usedmaterialsinclinicalpractice.Thereisawidevariability inoverallsurvivalofprostatecancerpatientswithobstructive uropathy,dependingondiseasecharacteristicsotherthanobstruction.Thelongestrecordedoverallsurvivalamountedto 26months [6].Thepresenteddatadonotallowacomparison ofoverallsurvivalforthethreeinterventionmodesPCN,retrogradestenting,andAD.Theresultssuggestinferioroverallsurvivalinpatientspre-treatedwithADorknownasAD resistantcomparedtohormone-naivepatients.Theseresults correspond with clinical experience in patients with other There are several problems concerning the validity and generalisabilityoftheseresultsbecausethepublishedstudies showanumberofprofoundmethodologicalflaws.Firstly,the numberofincludedpatientsperstudyissmall.Additionally, some studies report general results on various pelvic malignancieswithoutseparateanalysisofprostatecancerpatients. Asecondmajorissueconcerningthevalidityandcomparabilityofdataistheepidemiologicaldesignofthestudies.Most publisheddataarisefromcaseserieswithpotentiallyconsiderabledifferencesinpatientcharacteristics,whichmayhave a profound impact on differences in recorded outcomes and reduce the comparability of the results.…”