Impacto do índice de massa corporal sobre o desfecho de sobrevida em pacientes com câncer diferenciado de tireoide

www.bjorl.org

Brazilian

Journal

of

OTORHINOLARYNGOLOGY

ORIGINAL

ARTICLE

Impact

of

body

mass

index

on

survival

outcome

in

patients

with

differentiated

thyroid

cancer

夽

Yousif

Al-Ammar

_,

_Bader

_Al-Mansour

_,

_Omar

_Al-Rashood

_,

_Mutahir

_A.

_Tunio

_,

Tahera

Islam

_,

_Mushabbab

_Al-Asiri

_,

_Khalid

_Hussain

_Al-Qahtani

a_{KingSaudUniversity,CollegeofMedicine,DepartmentofOtolaryngology-Head&NeckSurgery,Riyadh,SaudiArabia} b_{KingFahadMedicalCity,RadiationOncology,Riyadh,SaudiArabia}

c_{KingSaudUniversity,CollegeofMedicineandResearchCenter,Riyadh,SaudiArabia}

d_{KingFahadMedicalCity,RadiationOncologyComprehensiveCancerCenter,Riyadh,SaudiArabia}

Received25June2016;accepted5February2017 Availableonline28February2017

KEYWORDS

Differentiatedthyroid cancers;

Bodymassindex; Overallsurvival; Diseasefreesurvival

Abstract

Introduction:Increasedbodymassindexisknowntobeassociatedwiththehighprevalence ofdifferentiatedthyroidcancers;howeverdataonitsimpactonsurvivaloutcomeafter thy-roidectomyandadjuvanttherapyisscanty.

Objective:Weaimedtoevaluatetheimpactofbodymassindexonoverallsurvivalanddisease freesurvivalratesinpatientswithdifferentiatedthyroidcancers.

Methods:Between 2000 and2011, 209patients with differentiated thyroidcancers (papil-lary,follicular,hurthlecell)weretreatedwiththyroidectomyfollowedbyadjuvantradioactive iodine-131therapyandthyroid-stimulatinghormonesuppression.Basedonbodymassindex, patientsweredividedintofivegroups;(a)<18.5kg/m2_{(underweight);(b)18.5---25kg/m}2

(nor-malweight);(c)26---30kg/m2_{(overweight);(d)31---40kg/m}2_{(obese)and(e)>40kg/m}2_(morbid

obese).Variousdemographic,clinicalandtreatmentcharacteristicsandrelatedtoxicityand outcomes(overallsurvival,anddiseasefreesurvival)wereanalyzedandcompared.

Results:Medianfollowupperiodwas5.2years(0.6---10).Meanbodymassindexwas31.3kg/m2

(17---72); body mass index 31---40kg/m2 _{was predominant (89 patients, 42.6%) followed by}

26---30kg/m2 _{seen in58 patients (27.8%).A total of18 locoregionalrecurrences (8.6%)and}

12distantmetastasis(5.7%)wereseen.The10yeardiseasefreesurvivalandoverallsurvival rateswere83.1%and58.0%respectively. Nosignificantimpactofbodymassindexon over-allsurvivalordiseasefreesurvivalrateswasfound(p=0.081).Similarly,multivariateanalysis showedthatbodymassindexwasnotanindependentprognosticfactorforoverallsurvivaland diseasefreesurvival.

夽 _{Pleasecitethisarticleas:Al-AmmarY,Al-MansourB,Al-RashoodO,TunioMA,IslamT,Al-AsiriM,etal.Impactofbodymassindexon}

survivaloutcomeinpatientswithdifferentiatedthyroidcancer.BrazJOtorhinolaryngol.2018;84:220---6.

∗_{Correspondingauthor.}

E-mail:kqresearch@hotmail.com(K.H.Al-Qahtani).

PeerReviewundertheresponsibilityofAssociac¸ãoBrasileiradeOtorrinolaringologiaeCirurgiaCérvico-Facial. https://doi.org/10.1016/j.bjorl.2017.02.002

1808-8694/©2017Associac¸˜aoBrasileiradeOtorrinolaringologiaeCirurgiaC´ervico-Facial.PublishedbyElsevierEditoraLtda.Thisisanopen accessarticleundertheCCBYlicense(http://creativecommons.org/licenses/by/4.0/).

Conclusion: Althoughbodymassindexcanincreasetheriskofthyroidcancer,ithasnoimpact ontreatmentoutcome;however,furthertrialsarewarranted.

© 2017 Associac¸˜ao Brasileira de Otorrinolaringologia e Cirurgia C´ervico-Facial. Published by Elsevier Editora Ltda. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/). PALAVRAS-CHAVE Câncerdiferenciado detireoide; Índicedemassa corporal; Sobrevidaglobal; Sobrevidalivrede doenc¸a

Impactodoíndicedemassacorporalsobreodesfechodesobrevidaempacientes comcâncerdiferenciadodetireoide

Resumo

Introduc¸ão: Sabe-sequeoaumentodoíndicedemassacorpóreaestáassociadoàalta prevalên-ciadecâncerdiferenciadodetireoide;entretanto,osdadossobreseuimpactonodesfechode sobrevivênciaapóstireoidectomiaeterapiaadjuvantesãoescassos.

Objetivo: Objetivou-seavaliaroimpactodoíndicedemassacorpóreanastaxasdesobrevida globalesobrevidalivrededoenc¸aempacientescomcâncerdiferenciadodetireoide.

Método: Entre 2000 e 2011, 209 pacientes com câncer diferenciado de tireoide (papi-lar/folicular/de células de Hürthle) foram tratados através de tireoidectomia, seguida de tratamento com iodo radioativo-131 adjuvante e supressão de hormônio estimulante da tireoide.Combasenoíndicedemassacorpórea,ospacientesforamdivididosemcincogrupos; (a)<18,5kg/m2_{(baixopeso);(b)18,5---25kg/m}2_{(pesonormal);(c)26-30kg/m}2_{(sobrepeso);(d)}

31-40kg/m2_{(obesos)e(e)>40kg/m}2_{(obesosmórbidos).Váriascaracterísticasdemográficas,}

clínicasedetratamentoetoxicidadeassociadaedesfechos(sobrevidaglobalesobrevidalivre dedoenc¸a)foramanalisadasecomparadas.

Resultados: Operíodomédiodeacompanhamentofoide5,2anos(0,6-10).Oíndicedemassa corpóreamédiofoide31,3kg/m2_{(17-72);oíndicedemassacorpóreade31-40kg/m}2_foi

pre-dominante(89pacientes,42,6%),seguidopor26-30kg/m2_{,observadoem58pacientes(27,8%).}

Observaram-se18recidivaslocorregionais(8,6%)e12metástasesdistantes(5,7%).Astaxasde sobrevidalivrededoenc¸aesobrevidaglobalde10anosforamde83,1%e58,0%, respectiva-mente. Nãofoi encontrado impactosignificativo doíndice de massa corpórea nastaxasde sobrevidaglobalousobrevidalivrededoenc¸a(p=0,081).Damesmaforma,aanálise multivari-adamostrouqueoíndicedemassacorpóreanãofoiumfatorprognósticoindependentepara sobrevidaglobalesobrevidalivrededoenc¸a.

Conclusão:Emboraoíndicedemassacorpóreapossaaumentaroriscodecâncerdetireoide, elenãotemimpactonoresultadodotratamento;contudo,outrosestudossãonecessários. © 2017 Associac¸˜ao Brasileira de Otorrinolaringologia e Cirurgia C´ervico-Facial. Publicado por Elsevier Editora Ltda. Este ´e um artigo Open Access sob uma licenc¸a CC BY (http:// creativecommons.org/licenses/by/4.0/).

Introduction

The prevalence of overweight body mass index (BMI) >30kg/m2 _{and obesity has increased worldwide during} past decade and data has shown that 35% of the Amer-icans are obese.1,2 _{In Kingdom of Saudi Arabia, BMI}

is increasing in both sexes and across all ages with an overall prevalence of 44%.3,4 _{Obesity is well known}

risk factor for various types of malignancies including endometrial carcinoma, colorectal carcinoma and breast carcinoma.5,6 _{Recent datahas reportedthecorrelation of}

increased BMI with differentiated thyroid cancer (DTC).7

A recent review has shown that morbid obese patients (BMI>35kg/m2_{) were found to have significantly larger} tumorsthanpatientswithBMI<35kg/m2_.8_{Similarly,another}

study from South Korea not only reported highest inci-denceofDTC inobesewomenbutalsocorrelationof DTC withhighermeanwaistcircumference,fatratio,andblood pressure.9

AlthoughthecausalrelationshipexistsbetweenBMIand DTC,its impacton treatment outcomes includingdisease free survival (DFS) and overall survival (OS) rates after thyroidectomy and Adjuvant radioactive iodine-131 (RAI) therapyandTSHsuppressionisnotwellknown.

Thepurposeofpresentstudywastoevaluatetheimpact ofBMIonlocoregionalcontrol(LRC),distantmetastasis con-trol(DMC),DFSandOS,andtoxicityprofileinSaudipatients withDTCtreatedwiththyroidectomyandadjuvantRAI ther-apy.

Methods

Afterformalapprovalfromtheinstitutionalethical commit-tee,medicalrecordsof209DTCpatients,whoweretreated atourhospitalduringtheperiodofJuly2000 and Decem-ber 2011, were reviewed using computer based database system.

Demographic,clinicopathologicalandradiological data

Demographic and clinical data including age at the time of diagnosis, gender and symptomatologywere reviewed. Differenthistopathologicalcharacteristics,includingtumor size,histopathologic variants, multifocality,tumor, lymph node and metastasis (TNM) staging were recorded. Data wascollectedfrom differentimagingmodalities including neck Ultrasonography (USG), whole body I-131 scintigra-phy (WBS), computed tomography (CT) scan of neck and chestandflourodeoxyglucosepositronemissiontomography (FDG-PET).Data regarding differenttreatment modalities including thyroidectomy, +/− neck dissection, adjuvant radioactiveiodine-131 (RAI)ablation and itsdoses in mil-licurie(mCi)werealsorecorded.

BMIcalculation

For the purpose of study, each patient was categorized accordingtoBMI.Heightandweightweremeasuredatthe timeofaccrualusinginstitutionalprotocolsandBMIwas cal-culated using the formula of weight in kilograms divided by the square of the height in meters (kg/m2_{). BMI was} then categorizedinto fivegroups asfollows: underweight as BMI<18.5kg/m2_{; normal weight as BMI from 18.5 to} 25kg/m2_{;overweightasBMIfrom25to30kg/m}2_;obeseas BMI from31 to 40kg/m2 _{and morbid obese as BMI above} 40kg/m2_.

Statisticalanalysis

The primaryendpointswere DFSand OSrates. Secondary pointswere;thecomparativeanalysisofdifferent clinico-pathologicalfeatures of DTCaccording to BMIcategories, LRCand DMCrates. Localrecurrence (LR)wasdefined as thedurationbetweensurgerydateanddateofclinicallyor radiologicallydetectablediseaseinthethyroidbedand/or incervicallymphnodesonimaging(USG,WBS,CTand FDG-PET)afterevaluationofelevatedthyroglobulin(TG)levels. DistantMetastasis(DM)wasdefinedasthedurationbetween surgerydate anddate ofdocumenteddisease outsidethe neckonimagingafterevaluatingforelevatedTG.DFSwas defined as the duration between surgery date and date ofdocumenteddiseasereappearance/relapse, deathfrom cancerand/orlastfollow-up.OSwasdefinedasthe dura-tionbetweensurgerydateanddateofpatientdeathorlast follow-up.

Chi-squareor Student’st-testswereusedtodetermine the differences in various clinical variables. Probabilities

of LRC, DMC, DFS and OS rates were shown with the

Kaplan---Meiermethodandthe comparisonforvarious sur-vival curves was performed using log rank. All statistical analyseswereperformedusingthecomputerprogramSPSS version16.0.

Results

Patient’scharacteristicsareshowninTable1.Therewerea totalof 209patients, 165 (79.0%)females and 44(21.0%)

Table1 Patients’characteristics.

Variable Wholecohort---n(%)

Totalpatients 209 Age(years) 41.1(16---78)SD±11.6 ≤45years 127(60.7) ≥45years 82(39.3) Gender Female 165(79.0) Male 44(21.0)

Femaletomaleratio 3.8

Typeofsurgery

Nearortotal thyroidectomy

189(90.4)

Lobectomy 20(9.6)

Lymphnodesurgery

Centralneckdissection 58(27.7) Lateralneckdissection 28(13.4)

Sampling 19(9.1) None 104(49.7) Meansize(cm) 2.3(0.1---10.0)±12.4 Histopathologicvariants Classic 162(77.5) Follicular 19(9.1) Hurthlecell 6(2.8) Tallcell 21(10.1) Sclerosing 1(0.5) Multifocal Yes 80(38.3) No 129(61.7) ETE Yes 41(19.6) No 168(80.4) LVSI Yes 39(18.6) No 170(81.4) Surgicalmargins Positive 21(10.1) Negative 188(89.9)

Lymphnodemetastasis

Yes 54(25.8)

No 183(87.6)

Backgroundthyroidtissue

Normal 64(30.6) Multi-nodulargoiter 68(32.6) Lymphocyticthyroiditis 45(21.5) Hashimotos’thyroiditis 32(15.3) DistantMetastasisat presentation 5(2.4) AJCCstaging I 107(51.2) II 36(17.2) III 53(25.4) IVA 10(4.8) IVB ---IVC 3(1.4) MeanpostoperativeTG (ng/mL) 1.39(0.1---42,890) BMI(kg/m2_{)mean 31.2(17---72)}

Table1 (Continued)

Variable Wholecohort---n(%)

BMIgroups <18.6 3(1.4) 18.6---25 43(20.6) 26---30 58(27.8) 31---40 89(42.6) >40 16(7.7) RAIdose No 53(25.4) 30mCi 64(30.6) 100mCi 45(21.5) 150---200mCi 47(22.5) RTtoneck 12(5.7)

n, number; SD, standard deviation; ETE, extrathyroid exten-sion;LVSI,lymphovascularspaceinvasion;AJCC,AmericalJoint CommissiononCancer;TG,thyroglobulin;BMI,bodymassindex; RAI,radioactiveiodine,mCi,millicurie;RT,radiationtherapy.

males. Classic type was the most predominant in 162 (77.5%) of patients. Multifocality was seen in 80 (38.3%), ETEwaspresentin 41(19.6%),andLVSIwaspresentin 39 (18.6%)ofpatients.Surgicalmarginswerepositiveinonly21 (10.1%)ofpatients.Lymphnodemetastasiswasnotedin54 (25.8%)ofpatients.Backgroundthyroidtissuewasnormalin 64 (30.6%),multinodular in68 (32.6%), lymphocytic in 45 (21.5%) and Hashimoto’s in 32 (15.3%). There were 189 (90.4%) who underwent near or total thyroidectomy, and theremaining20(9.6%)underwentlobectomy.Centralneck dissectionwasdonein58(27.7%)ofpatients.Nearortotal thyroidectomywasperformedonmostofthepatientswho had classic papillary thyroid carcinoma. Those who were referred from other hospital to this tertiary center after undergoinglobectomy,weretreatedbytotalthyroidectomy ascompletion.Lobectomywasreservedonlyforthose indi-viduals whose tumor wasrestricted only in one lobe and there was noevidence of intrathyroidal metastasis. Cen-tralneckdissectionwasperformedinpatientswithenlarged lymphnodesatthetimeofsurgeryoridentifiedoncervical ultrasonography.

Complicationsandtoxicities

Post-thyroidectomycomplicationrateswereminimal; per-manent hypocalcemia was seen in four patients (1.9%) and no correlation was seen with BMI (p=0.063). Over-all, RAI ablation was tolerated well without any Grade 3 or 4 side effects; however, acute and late(Grade --- 3/4) complications were seen significantly 16 patients (7.66%) withnoassociationwithBMI(p=0.71).

Treatment

outcomes

Median follow up period was 5.2 years (range: 0.6---10). For whole cohort, the 5 year LRC and DMC rates were 91.4% and 94.3% respectively. Total 18 LRs (8.6%) were observed; 2 in BMI 18.6---25kg/m2_{, 9 in BMI 26---30kg/m}2_,

4 in BMI 31---40kg/m2 _{and 3 in BMI >40kg/m}2 _(p=0.051).

The LRswere salvagedbysurgery; lateralneck dissection

1.0 0.8 0.6 kg/m2 < 18.5 18.6 < 25 > 40 < 18.5-censored 26−30-censored > 40-censored 31−40-censored 18.6 < 25-censored 26−30 31−40 0.4 0.2 0.0 2.00 4.00 6.00 Follow-up (years)

Disease free sur

viv

al probability according to BMI g

roups

8.00 10.00

Log rank p value 0.056

Figure1 Kaplan---Meiercurvesofdiseasefreesurvival accord-ingtoBMIgroups.

1.0 0.8 0.6 0.4 0.2 0.0 Sur viv

al probability according to BMI g

roups 2.00 4.00 Follow-up (years) 6.00 8.00 10.00 kg/m2 < 18.5 18.6 < 25 > 40 < 18.5-censored 26−30-censored > 40-censored 31−40-censored 18.6 < 25-censored 26−30 31−40 Log rank p value 0.081

Figure2 Kaplan---Meiercurvesofoverallsurvivalaccordingto BMIgroups.

(10 patients); completion thyroidectomy (4 patients) and excision(4patients)followedbyRAIablation(14patients). Similarly, total 12 DM (5.7%) were observed; 6 in BMI 26---30kg/m2_{,3inBMI31---40kg/m}2_{and3inBMI>40kg/m}2

(p=0.062).DMsweresalvagedbyRAIablationandpalliative irradiation(onepatient).

The overall 5 year DFS rate was 92.8%. Furthermore, theDFSforthepatientswithBMI18.6---25kg/m2_wasworse

than those patients who have BMI of 26---30kg/m2 _and

31---40kg/m2_{, although the difference was not significant}

(p=0.056)(Fig.1).Theoverall5yearOSratewas94.1%.No significantdifferencewasinBMIgroups(p=0.081)(Fig.2). Onmultivariateanalysis,importantprognosticfactorsfor DFSand OSwere age,AJCC staging, lymphnode involve-ment,LVSIandadjuvantRAItherapy.BMIwasfoundnotan importantindependentprognosticator(Table2).

Table2 Multivariateanalysisofvariablesondiseasefreesurvivalandoverallsurvival.

Variable Diseasefreesurvival Overallsurvival

p-Value OR(95%CI) p-Value OR(95%CI) Age(<45vs.45years) 0.033 0.83(0.90---2.50) 0.041 0.50(0.10---2.41) Cormorbids(yesvs.no) 0.091 1.28(1.07---1.97) 1.00 1.80(0.79---2.10) AJCCstage(<IIvs.>II) 0.041 0.67(0.60---1.34) 0.01 0.85(0.80---1.90) Nstage(N0vs.N1) 0.033 0.81(0.79---2.00) 0.051 1.21(1.10---2.10) BMIkg/m2_{(>30vs.<30) 0.052 1.15(1.0---2.45) 0.061 1.15(1.01---1.65)}

LVI(novs.yes) 0.031 0.91(0.76---1.45) 0.60 1.10(0.89---2.00) AdjuvantRAI(yesvs.no) 0.031 0.50(0.10---2.41) 0.041 0.50(0.67---2.81)

OR,oddsratio;95%CI,95%confidenceintervals;AJCC,AmericanJointCommissiononCancer;N,node;BMI,bodymassindex; LVI, lymphovascularinvasion;RAI,radioactiveiodine.

Table3 SummaryofeffectofBMIonheadandneckcancerpatients.

Authors,Years BMIcategories Treatmentmodality EffectofBMI Takenakaetal.,15_{2015 Obeseoroverweight(25kg/m}2_),

normal(18.5kg/m2_and

<25kg/m2_{),andunderweight}

(<18.5kg/m2_).

Surgery,CRT,RT 192surgicallytreatedpatientsno statisticallysignificanttheeffect ofBMIonoverallsurvival.

Inothertreatmentmodalitieshigh BMIwasassociatedwithabetter prognosis.

HuangPYetal.,17_{2013 Obese(27.5kg/m}2_),overweight

(23.0---27.4kg/m2_{),normalweight}

(18.5---22.9kg/m2_{),underweight}

(<18.5kg/m2_).

IC+CCRT HigherBMIwasassociatedwith increasedfailurefreesurvivaland overallsurvival.

IC+RT Noinfluenceontheriskof locoregionalrecurrences. LinYHetal.,18_{2015 Twogroups(<23kg/m}2_vs.

≥23kg/m2₎

IMRT,CCRT, RT/CCRT+IC

BMIwasnotsignificantly associatedwithoverallsurvival, diseasespecificsurvival,distant metastasisfreesurvival,or locoregionalfreesurvival. vanBokhorst---devander

SchuerB.etal.,21

1999

BMInotcalculated,Percentageof weightlossduringthe6months beforetreatment,thepercentage ofidealbodyweight,serum albumin,totallymphocytecount, nutritionalindex,and

bioelectricalimpedanceanalysis.

Surgery Noneofthestudiednutritional parameterswereassociatedwith survival.

Presentstudy Morbidobese(>40kg/m2_),obese

(31---40kg/m2_),overweight

(26---30kg/m2_{),normalweight}

(18.5---25kg/m2_{),underweight}

(<18.5kg/m2_).

Surgery BMIwasnotsignificantly associatedwithoverallsurvival, diseasefreesurvival

CRT,chemoradiationtherapy;RT,radiationtherapy;CCRT,concurrentCRT;BMI,bodymassindex;IC,inductionchemotherapy;IMRT, intensity-modulatedradiotherapy.

Discussion

ObesityisoneoftheendemicHealthissuesinthedeveloped countries.Itisaknownriskfactorforseveraldiseases,an increasedriskofdevelopingendometrial,prostate,breast, pancreaticandthyroidcancerexistsintheobese.10 _Inour

study we tried to sort out the correlation between BMI andsurvivalrates inpatientswithDTC.Tothebestofour

knowledge,thisisthefirststudytomentionimpactofBMI ontheprognosisofpatientswithDTC.

Ourfindingssuggest that BMI does nothave an impact on OS of DTC patients treated surgically. Although our resultsdidshowthattheDFSintheunderweightpatient’s was worse than the normal and overweight group, it did not reach statistical significance. Further, univariate and multivariateanalysesrevealedageandAJCCstagingas

inde-pendent prognostic factor for both DFS and OS. Also N stageofthedisease,lymphovascularinvasionandadjuvant radioactiveiodinewassignificantlyassociated withDFSin univariateandmultivariateanalysis(Table2).

Impact ofBMIonsurvivaloutcomeshasbeenstudiedin variousmalignanciessuchasbreastandgastriccancers.11---13

However,few studies have evaluatedtheBMI andobesity as a prognostic factor in head and neck malignancies.14

Takenakaetal.identifiedpretreatmentBMIasan indepen-dentprognosticfactorforsurvivalamongpatientswithhead and neck squamous cell carcinoma (HNSCC) treated with chemoradiation,in theirstudythepopulation wasdivided in tothreegroups: underweight (18.5kg/m2_<BMI),normal weight (18.5---25kg/m2_{) and overweight (25kg/m}2_>BMI), and they noted that the overweight patients had the most favorable prognosis, and the underweight patients theworst.15 _{Similarly,studies byShen etal.,}16 _andHuang

et al.,17 _{found high BMI to be strongly associated with}

betteroverallsurvival,disease-specificsurvivaland failure-freesurvival.DataofboththestudiessuggestedBMIasan independentprognosticfactorinpatientswith nasopharyn-geal carcinoma (NPC). HoweverLin etal.18 _{study did not}

revealanyassociationbetweenpretreatmentBMIand over-allsurvival,diseasespecificsurvival,distantmetastasisfree survival,orlocoregionalfreesurvivalinpatientswithNPC (Table3)

Several studies suggested similar to our findings that other risk factors, such asage and stage;15 _{nodal status,}

aggressivehistopathologicvariants,multifocality,ETE,LVSI and adjuvant RAI are more important clinicopathological predictorsthanBMIinDTC.19,20

Takenaka et al.15 _{inferred that different treatment}

modalitiesinfluencestheimpactof BMIonprognosis.This might explainthe disparity between theresults of differ-ent studies, including our study.Small number of studies discussed theBMIasaprognosticfactor inheadand neck malignanciestreatedbysurgery.AstudybyTakenakaetal.15

and another by van Bokhorst-de van der Schuer et al.,21

involved 192 and 64 patients respectively, with head and neck malignances treated surgically, concluded that the impactofBMIontheprognosiswasnotstatistically signifi-cant.WhereastheOSwassignificantlybetterinthepatients withhigherpretreatmentBMIreceivingchemoradiationand radiationtherapy.MoreoverBMIdidnotcomeupasan inde-pendentprognosticfactorintheresultofCoxproportional hazardanalysisinsurgicallytreatedpatients.15

Severalreasonswereexplainedinthestudiesshowinga positiveimpactofBMIonthesurvivalofpatientswithhead andneckmalignancies.Firstof all,themodalityof treat-ment, patients with head and neck malignancies treated by chemotherapy and/or radiation were found to have a morefavorableprognosisiftheywereinahighBMIgroup, however, this relation was not seen in patients treated surgically.15,17 _{Secondly,CancerCachexiawhichisaknown}

challengeintreatingpatientswithmalignanciessuchas pan-creatic,gastricandheadandneckcancers.17,22_Cachexiacan

decreasetreatmentresponseandaffecttheimmunesystem capability infighting infections,which leadstodeath.17,22

Inourstudythepossiblereasonsfor theinsignificant find-ings were:the treatment which wasby Surgery and(RAI) ablation,witha94.1%5yearOSrateandcancercachexia whichwasnotseeninthestudygroup.AdditionallyInour

cohort,postthyroidectomycomplicationswereminimaland patientstoleratedadjuvantRAIablationverywellwith min-imaltoxicity.

Ourstudyhadseverallimitations,firsttheretrospective natureofpresent study andsecond thesmallsample size of 209 patients. Besides these two, our study population is mainlyMiddle Eastern or Asiandescendants, additional studiesinotherpopulationsarewarranted.

Conclusion

In conclusion, although BMI is known to increase the risk of thyroid cancer, and it is a strong prognostic factor in thehead andneck cancersassociated withcachexia,and treatedwithchemoradiationorradiationtherapy;itisnota strongpredictorforthetreatmentoutcomeinDTCpatients.

Conflicts

of

interest

Theauthorsdeclarenoconflictsofinterest.

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