title: Laser-induced hyperthermia in rat prostate cancer: role of site of tumor implantation.
abstract: OBJECTIVE
  To investigate the importance of the site of tumor implantation on the treatment response to laser-induced hyperthermia (LIH) of rat prostate cancer (PCa), because interventional manipulations of PCa have been reported to increase metastatic dissemination.
  
  
  METHODS
  Seven to nine days after either subcutaneous or orthotopic implantation of MatLyLu cells, LIH (46.5 degrees C) was induced using pulsed irradiations of a neodymium:yttrium-aluminum-garnet laser. Both local control and distant metastases were evaluated. Plasma metalloproteinase 9 (MMP-9) was tested as a possible marker of PCa progression and LIH response.
  
  
  RESULTS
  Twelve days after LIH treatment of subcutaneous tumors, the volumes were reduced by 64% after 8 minutes of irradiation, 73% after 10 minutes, 81% after 15 minutes, and 91.1% after 20 minutes. In the orthotopic model, the corresponding tumor reductions were 44% after 10 minutes, 61% after 20 minutes, and 65% after 30 minutes. Lung metastases were observed in only 1 animal with subcutaneous tumors. In contrast, 86% of the orthotopic tumor-bearing animals treated for 30 minutes had lung metastases compared with 23% of the untreated tumor-bearing rats. MMP-9 expression was detected in both orthotopic and subcutaneous tumor tissue and in the plasma of tumor-bearing rats. The prostate tissue of healthy rats and subcutaneous tumor-bearing rats was devoid of MMP-9. The plasma levels of MMP-9 showed a trend toward direct correlation with local tumor control but no correlation with the incidence of metastasis.
  
  
  CONCLUSIONS
  These data emphasize the importance of the site of tumor implantation for evaluation of the efficacy of therapeutic interventions and may warrant further studies before widespread clinical application of LIH as monotherapy.
authors.affiliation: Wellman Laboratories of Photomedicine, Massachusetts General Hospital, Harvard Medical School, Boston 02114, USA.
authors.forename: M
authors.initials: M
authors.lastname: Lein
authors.forename: F
authors.initials: F
authors.lastname: Koenig
authors.forename: J
authors.initials: J
authors.lastname: Misdraji
authors.forename: W S
authors.initials: WS
authors.lastname: McDougal
authors.forename: K
authors.initials: K
authors.lastname: Jung
authors.forename: S A
authors.initials: SA
authors.lastname: Loening
authors.forename: T
authors.initials: T
authors.lastname: Hasan
authors.forename: B
authors.initials: B
authors.lastname: Ortel
mesh_terms: D000818:Animals; D006979:Hyperthermia, Induced / Q000379:methods*; D053685:Laser Therapy; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000096:biosynthesis; D009374:Neoplasms, Experimental / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D051381:Rats
chemical_list: D020780:Matrix Metalloproteinase 9