INTRODUCTION

TherewererecordsthatancientcivilizationsinEgypt, India,China,andGreekemployedsunexposuretotreatskindis-eases,ricketsandevenpsychosis.However, ithasnotbeenemployedwidelyinmedicineuntiltheeighteencentury[1].In1903,ThegroupofVonTappeinerfoundfavorableresultafter

photodynamictherapy(PDT)usingseveraldyes:eosin,fluo-rescein,sodiumdichloroanthracenedisulfonateand‘Grubler’sMagdalenered’with lightonskindiseases,suchas lupusoftheskinandcondylomataofthefemalegenitalia[2].VonTappeinerandJodlbauer[3,4]provedthenecessityofoxygeninthisphenomenonin1904andin1907,theyexplainedthisphenomenonwithoxygen-dependentphotosensitizationandadoptedaterm“photodynamictherapy”.Althoughtheseshowedgoodresults,nofurther reportswere forthcomingbecauseof theemergenceof ionizing radiation incancertherapy.Diamondetal.[5]reportedin1972thathematopor-phyrinactivatedbywhitelightmayleadtoregressionofanexperimentalgliomainrats.Finally,Doughertyetal. [6] initi-atedclinicaltrialsofPDTin25patientswithcutaneousandsubcutaneoustumorsandconfirmedtheeffectivenessofPDT.

Original Article

Photodynamic therapy for breast cancer in a BALB/c mouse modelTae-Gyu Ahn1, Byoung-Rai Lee2, Eun-Young Choi1, Dong Won Kim3, Sei-Jun Han1

Departments of 1Obstetrics and Gynecology and 2Biochemistry, Chosun University School of Medicine, Gwangju; 3Department of Obstetrics and Gynecology, Mirae and Heemang Women’s Hospital, Gwangju, Korea

Received Nov 11, 2011, Revised Dec 12, 2011, Accepted Dec 20, 2011

This abstract was adopted as a poster presentation in 2011 Asian Society of Gynecologic Oncology 2nd Biennial Meeting.

Correspondence to Sei-Jun HanDepartment of Obstetrics and Gynecology, Chosun University School of Medicine, 309 Pilmun-daero, Dong-gu, Gwangju 501-759, Korea. Tel: 82-62-220-3085, Fax: 82-62-232-2310, E-mail: sjhan@chosun.ac.kr

pISSN 2005-0380 eISSN 2005-0399

Copyright © 2012. Asian Society of Gynecologic Oncology, Korean Society of Gynecologic Oncology

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Objective:Photodynamictherapy(PDT)hasbeenusedforsuperficialneoplasmsanditsusagehasbeenrecentlyextendedtodeeperlesions.ThepurposeofthisstudywastoobservewhetherornotPDTcancurebreastcancerinthesolidtumormodel,andtodefinethecriticalpointoflaseramountforkillingthecancercells.Methods: Twenty fourBALB/cmousemodelswithsubcutaneousEMT6mammarycarcinomaswereprepared.Miceweredividedintoeightgroupsdependingontheamountofillumination,andthetumorsizewasbetween8mmand10mm.Webeganbyperitoneal infiltrationwithaphotosensitizer48hourspriortoapplyingthelaser light,andthenweappliedanon-thermallaserlight.Theenergywasfrom350J/cm2to30J/cm2tothecancer.Results: Regardlessofthetumorsizefrom8mmto10mm,allmiceapparentlyshowedpositiveresultsviaPDT.Wealsodidnotfindanyrecurrenceover90J/cm2.Inallmodels,thecolorofthebreastcancerlesionsbegantovarytodarkon2dayspostPDTandthetumorregressionbegansimultaneously.Also,weconfirmedthecompleteregressionofthebreastcancer21daysafterPDT.Conclusion: WeconfirmedthatPDTmaytreatbreastcancersthataresizedless10mminmousemodels.Themoderateenergytodestructthebreastcancercellsmaybe90J/cm2.Therefore,wecanexpectthatPDTmaybeutilizedtotreatbreastcancer,butweneedmoreexperience,skillsandprocessingforclinicaltrials.

Keywords:Breastneoplasms,InbredBALBC,Mice,Photodynamictherapy

J Gynecol Oncol Vol. 23, No. 2:115-119http://dx.doi.org/10.3802/jgo.2012.23.2.115

Tae-Gyu Ahn, et al.

http://dx.doi.org/10.3802/jgo.2012.23.2.115116 www.ejgo.org

Afterthe1990s,PDThasrapidlybecomearelevantmethodbothinclinicalapplicationandbasicmechanisticunderstand-ing in treating theskinandsuperficialcancerous lesions.NowPDTwithPhotofrinhasbeenapprovedbytheUSFoodandDrugAdministration(FDA)andnumerousotherhealthagenciesthroughouttheworld forobstructiveesophagealcancerandlungcancer,bladdercancer,etc[7].RecentlyPDThasbeenclinicallyapplicableinsuperficiallesionslikeskinle-sions,cervical intraepithelial lesionsandhollowedorgans. Inourgynecologicdepartment,wehavemuchcumulativedataoftheeffectofPDToncervical intraepithelialneoplasiaandhavestartedtotreatbreastcancer.However,therearetodatenodataoftheeffectofPDTinthefieldofthebreast.SoweherebyexaminedtheresponseofbreastcancerstoPDTwithPhotofrinusingmurinemodels.

MATERIALS AND METHODS

1. Tumor modelBreastcancercells(EMT-6)wereobtainedfromtheAmeri-

canTypeCultureCollection(ATCC;Manassas,VA,USA)and

maintained inWaymouth’smediasupplementedwith15%fetalbovineserumand1%penicillin-streptomycinsolution.6-week-oldfemaleBALB/cmice(Samtako,Osan,Korea)wereanesthetizedwithketamineand1.5×105cellsweresubcuta-neouslyinjectedintothelowerback.Foreachexperiment,3micewereusedineachexperimentalgroupandtreatmentwasstartedwhentheaveragetumorsizewasapproximately250mm3.Thestudywasapprovedbythelocalanimalwelfarecommittee.

2. Protocol of PDTWebeganbyperitonealinfiltrationofphotosensitizer(Pho-

tofrin[HpD],AxcanPharmaInc.,Mont-Saint-Hilaire,Canada)with5mg/kg,48hourslater,weappliedanon-thermallaserlight(CeralasDiodeLaser632System,Biolitec,Jena,Germany)(Fig.1).Theamountofenergywasfrom350J/cm2to30J/cm2onthecancercellandthemarginoflaserwasalittlebitwiderthanthecancerlesionbecausecancercanrecureasily.Thenweevaluatedtheeffectsofthisprocedureevery3days.Thecontrolgroupwasnotneededbecauseifthebreastcancerwasnot irradiated, thegrowthofcancerwillcertainlycon-tinue.

RESULTS

JustafterPDT,graydiscolorationwasshownattheillumina-tionsite.Thecolorofilluminationsiteincludingbreastcancerbegantodarken2dayspostPDTandthecancerregressedsi-multaneously.Thetumorsizewasfrom8mmto10mm,how-ever,regardlessofthetumorsizeallcancermodelsshowedeffectivenessof thePDT.However, tissuedeformitieswerenoticedinthe240and350J/cm2group(Fig.2).Weconfirmedthecompleteremission21dayspostPDTfrom180to90J/cm2(Fig.3).From350J/cm2to90J/cm2,allmicemodelsshowedcom-

pleteremission.HoweveroneoutofthreemiceshowednoFig. 1. Photodynamic therapy illumination onto the cancer with a non-thermal laser light (Ceralas Diode Laser 932 System).

Fig. 2. Complete remission was shown in 350 and 240 J/cm2 but tissue deformities were noticed because of high energy (21 days after photodynamic therapy).

Effect of photodynamic therapy on breast cancer model

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responseinthe60J/cm2group(Fig.4)andinthe30J/cm2group,theeffectivenessofPDTdidnotshowinallmice(Fig.5).So,wedeterminedthatthemoderateenergyrequiredtotreatbreastcancersizedlessthan10mmisaround90J/cm2.Wedidnotfindanyrecurrenceinthegroupthatreceivedenergymorethan90J/cm2.So,theenergyof90J/cm2maybeminimumenergyrequiredtodestructthebreastcancercellscompletely.

DISCUSSION

PDT isa treatment thatcaneradicatepremalignantandearly-stagedcancerandcanreducethetumorsize inend-stagedcancers.TheadvantageofPDTisthatitisaminimallyinvasivemethodthatcanaffecttheselectiveareaandthereisnolimitationofrepetitionsandlittlecomplications.Itisalso

Fig. 3. Complete remission shown in 180, 150, 120, and 90 J/cm2 (21 days after photodynamic therapy).

Fig. 4. The first and third mice showed complete remission but the second one (arrow) revealed no response with 60 J/cm2 (21 days after photodynamic therapy).

Fig. 5. All mice showed no response. Cancer growth was continued with 30 J/cm2 (21 days after photodynamic therapy).

Tae-Gyu Ahn, et al.

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hasamerit inthatPDTisapplicablewhensystemicchemo-therapyandsurgeryarenotpossible[8].PDTmechanismcanbeexplainedbytwoparts:uptakeofsensitizersandtumordestructionbylaserlight.

1. PDTThefirstapprovalofPDTwasinCanadain1993forthetreat-

mentofbladdercancers.EsophagealcancerwasapprovedbytheUSFDAinDecember1995,andearlynon-smallcell lungcancer in1998followedbyBarrett'sesophagus[9,10].EventhoughPDTdataingynecologyarenotsufficient,several in-stitutesalreadyhavecollectedmuchdataandsomegyneco-logicdepartmentshavetriedtobeginPDT.Severalphotosen-sitizersthatcanbeaccumulatedinthetumortissueselectivelyhavebeen introduced,but theexactmechanismsofeachphotosensitizersaredifferent.Porphyrinderivativescanbelocalizedintumorswheninjectedintothebloodstream[11].Inthehematoporphyrinderivativeandits improvedversion,calledPhotofrin,arestillthemostwidelyusedphotosensitiz-ersinPDToftumors[12].Amongphotosensitizers,Photofrinhasbeenusedinourdepartmentforthe lasttenyearsandweassumedthatPDTwithPhotofrinmaybehaveeffectiveinbreastcancersalso. Inourdepartment,webegantooperateonbreastcancerfrom2010andwetriedtoadoptPDTinthebreast lesions.So,weconductedthisstudy.Weappliedthesameprotocolthatwasusedinpatientstothemicemodel.Thedrugisinjectedintravenouslyandafter48hours,applica-tionofirradiationtotumorswasperformedwith630nmwavelengthoflaser[13,14].

2. PDT and breast cancerPDThasbeenapplicableinthefieldsothatphysicianscan

directlyapproachthe lesion.Thebreastarea isalsoabletobeapproacheasily,andwecanadoptPDTforthebreast.Thefirst linetreatmentforbreastcancer issurgeryandcanleadtochangesinthebreastshape.Thus,ifthereisanon-invasiveprocedurethatisabletodestroycancercells,itwouldbepref-erable.EventhoughtherewerenoreportsaboutPDTforthebreastcancerasthefirstlinetherapy,severalstudiesshowedreliableeffectsofPDT in locally recurrentbreastcancerorchestwallrecurrence[15-17].Thus,wemayassumethroughthisdatathatbreastcancercellsmaybeeradicatedbyPDT.Also,PDTisapplicableduringsurgery.Aftermastectomy,PDTcanbeappliedonthebedofthepreviouslesionforprevent-ingrecurrence.TheusuallaserfibercanbeusedwhenPDTisappliedtotheskinareasuchaschestwallrecurrence.But ifwetrytotreatthelesionthatislocatedundertheskin,aspe-cificlaserfiberisneededsuchasaninterstitialtypethatcanpenetratetheskinandreachthelesion.So,researchaboutthe

specificlaserfiberismandatorytodestroylesionsundertheskin.Fromourstudy, firstwecanreconfirmthePDTeffects to

destroybreastcancercells.Next,discoveryofproperenergyisvery importantbecausetheamountofenergyshouldbedifferentforeachtissueandorgan(forexample,weapplied240J/cm2touterinecervicalcancer).Inaddition,whenphoto-chemical internalization(PCI)conceptisaddedtotraditionalPDT,theresultofcancercelldestructioncanbemaximized.ForperformingPCI, chemotherapeuticagents shouldbeaddedbeforePDT.Whenpreviouslyinfiltratedsensitizersareexposedto light,sensitizersbegintoactivateandproducefreeradicals.Finally,endocytosedmoleculesorchemothera-peuticagentsmaybereleasedandattackcancercellsdirectlybeforebeingdegradedbylysosomes[18].Thus,ifweaddthisPCIconceptwiththetraditionalPDTinournexttrial,wecanassumethattheresultswillimprovemarkedly.InourresearchwewereabletoconfirmtheeffectofPDT

onbreastcancermodelsandfoundouttheproperamountofenergyof90J/cm2inlessthan10mmsizedbreastcancers.However,weassumethatweneedmoretechnicalpracticeandclinicaldatatobeabletoapplyPDTtohumans.

CONFLICT OF INTEREST

Nopotentialconflictof interestrelevanttothisarticlewasreported.

ACKNOWLEDGMENTS

ThisresearchwassupportedbyresearchfundsfromChosunUniversity,2005.

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