title: Thermotherapy using magnetic nanoparticles combined with external radiation in an orthotopic rat model of prostate cancer.
abstract: BACKGROUND
  We evaluated the effects of thermotherapy using magnetic nanoparticles, also referred to as magnetic fluid hyperthermia (MFH), combined with external radiation, in the Dunning model of prostate cancer.
  
  
  METHODS
  Orthotopic tumors were induced in 96 male Copenhagen rats. Animals were randomly allocated to eight groups, including controls and groups for dose-finding studies of external radiation. Treatment groups received two serial thermotherapy treatments following a single intratumoral injection of magnetic fluid or thermotherapy followed by external radiation (10 Gy). On day 20, after tumor induction, tumor weights in the treatment and control groups were compared and iron measurements in selected organs were carried out.
  
  
  RESULTS
  Mean maximal and minimal intratumoral temperatures obtained were 58.7 degrees C (centrally) and 42.7 degrees C (peripherally) during the first thermotherapy and 55.4 degrees C and 42.3 degrees C, respectively, during the second of two treatment sessions. Combined thermotherapy and radiation with 20 Gy was significantly more effective than radiation with 20 Gy alone and reduced tumor growth by 87.5-89.2% versus controls. Mean iron content in the prostates on day 20 was 87.5% of the injected dose of ferrites, whereas only 2.5% was found in the liver.
  
  
  CONCLUSIONS
  An additive effect was demonstrated for the combined treatment at a radiation dose of 20 Gy, which was equally effective in inhibiting tumor growth as radiation alone with 60 Gy. Serial heat treatments were possible without repeated injection of magnetic fluid. The optimal treatment schedules of this combination regarding temperatures, radiation dose, and fractionation need to be defined in further experimental studies.
authors.affiliation: Department of Urology, Charité University Medicine, Campus Mitte, Berlin, Germany. manfred.johannsen@charite.de
authors.forename: Manfred
authors.initials: M
authors.lastname: Johannsen
authors.forename: Burghard
authors.initials: B
authors.lastname: Thiesen
authors.forename: Uwe
authors.initials: U
authors.lastname: Gneveckow
authors.forename: Kasra
authors.initials: K
authors.lastname: Taymoorian
authors.forename: Norbert
authors.initials: N
authors.lastname: Waldöfner
authors.forename: Regina
authors.initials: R
authors.lastname: Scholz
authors.forename: Serdar
authors.initials: S
authors.lastname: Deger
authors.forename: Klaus
authors.initials: K
authors.lastname: Jung
authors.forename: Stefan A
authors.initials: SA
authors.lastname: Loening
authors.forename: Andreas
authors.initials: A
authors.lastname: Jordan
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D006979:Hyperthermia, Induced / Q000379:methods*; D008280:Magnetics; D008297:Male; D049329:Nanostructures; D011471:Prostatic Neoplasms / Q000532:radiotherapy* / Q000628:therapy*; D011878:Radiotherapy / Q000379:methods; D011879:Radiotherapy Dosage; D051381:Rats