title: Effect of blood flow occlusion on laser hyperthermia for liver metastases.
abstract: BACKGROUND
  Interstitial laser hyperthermia (ILH) is an in situ ablative technique for the treatment of colorectal liver metastases. A significant factor limiting tumor destruction is hepatic blood flow. Modulation of hepatic blood flow may increase the size of tumor necrosis achieved. Our aim was to investigate the effect of blood flow occlusion on ILH-induced necrosis in both tumor and normal liver tissue.
  
  
  METHODS
  A model of colorectal liver metastases in male inbred CBA mice was used. ILH was applied to normal liver and tumor tissue using a bare optical quartz fiber from an SYL500 Nd:YAG surgical laser generator, with and without hepatic blood flow occlusion, and the extent of necrosis was studied. Tumor blood flow was assessed by laser Doppler flowmetry and scanning electron microscopy.
  
  
  RESULTS
  Hepatic blood flow occlusion resulted in a significant reduction in blood flow in normal liver tissue (37.9% +/- 5.8, P < 0.001) and in the periphery of the tumor (17.5% +/- 7.8, P < 0.001). It did not affect the blood flow in the center of the tumor (13.4% +/- 4.3, P = 0.07). ILH of normal liver tissue, at low power (2 W), with hepatic blood flow occlusion, resulted in a significant increase in the diameter of necrosis. This effect was not seen when higher power (5 W) was used in normal liver. No significant effect was noted within tumor tissue at either power setting.
  
  
  CONCLUSIONS
  The overall effect of hepatic blood flow occlusion in ILH-induced tissue necrosis appears to be negligible in tumor tissue. Its main applicability appears to be at the tumor-host interface, where a decrease in blood flow may lead to higher temperatures and therefore to a greater degree of tumor cell destruction.
authors.affiliation: Department of Surgery, Alfred Hospital, Monash University, Commercial Road, Prahran, 3181, Australia.
authors.forename: V
authors.initials: V
authors.lastname: Muralidharan
authors.forename: C
authors.initials: C
authors.lastname: Malcontenti-Wilson
authors.forename: Chris
authors.initials: C
authors.lastname: Christophi
mesh_terms: D000818:Animals; D015179:Colorectal Neoplasms / Q000473:pathology*; D004195:Disease Models, Animal; D006979:Hyperthermia, Induced; D017078:Laser-Doppler Flowmetry; D007834:Lasers; D008099:Liver / Q000098:blood supply* / Q000473:pathology; D008113:Liver Neoplasms / Q000098:blood supply / Q000556:secondary* / Q000628:therapy; D008297:Male; D051379:Mice; D008808:Mice, Inbred CBA; D008855:Microscopy, Electron, Scanning; D009336:Necrosis