title: Effect of carbogen on tumour oxygenation and 32P-colloid interstitial irradiation response.
abstract: BACKGROUND
  Interstitial irradiation therapy using radionuclides is a slow and continual process in which the effect is exerted gradually, thus improvement of the hypoxic status of the tumor will also take a long time. It has been known that carbogen delivery of 5-15 min increases tumor oxygenation. However, the long-term effect of carbogen breathing on hypoxic cells has not yet been determined, and little is know about the effect of carbogen breathing for sensitization to interstitial irradiation therapy.
  
  
  METHODS
  99mTc-HL91(99mTc 4,9-diaza-3,3,10,10-tetramethyldodecan-2,1-dione dioxime) hypoxic imaging was performed in 10 mice bearing sarcoma 180 (S180) before and after 2 h carbogen breathing. Radioactivity ratios of tumor to contralateral limbs (T/L) of the 2 images were calculated and compared. Mice bearing S180 were subjected to long-term carbogen breathing (2 h/day for 24 days), and were treated with or without 32P-colloid. Tumor growth rate was observed in the S180-bearing mice.
  
  
  RESULTS
  T/L of 99mTc-HL91 uptake before and after carbogen breathing was 1.872+/-0.391 and 1.354+/-0.189, respectively (t=4.476, P<0.01). In mice in the 32P-treated air breathing group and 32P-treated carbogen breathing group, tumor growth rate did not differ on day 12 after 32P-colloid treatment, and on day 24 the tumor volume was 2.728+/-0.469 and 2.237+/-0.603 cm3 (t=2.128, P<0.05), respectively, with tumor mass being 2.437+/-0.447 and 1.965+/-0.538 g (t=2.134, P<0.05), respectively.
  
  
  CONCLUSIONS
  Long-term carbogen breathing can increase tumor oxygenation and continual carbogen breathing is necessary for enhancing the therapeutic effect of 32P-colloid interstitial irradiation.
authors.affiliation: Department of Nuclear Medicine, Second Affiliated Hospital of Zhejiang University College of Medicine, Hangzhou, People's Republic of China. zhanhw@hotmail.com
authors.forename: Hong Wei
authors.initials: HW
authors.lastname: Zhan
authors.forename: Hong Biao
authors.initials: HB
authors.lastname: Liu
authors.forename: Cheng Kan
authors.initials: CK
authors.lastname: Bao
authors.forename: Xiao Juan
authors.initials: XJ
authors.lastname: Ye
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Gang Qiang
authors.initials: GQ
authors.lastname: He
mesh_terms: D000818:Animals; D001918:Brachytherapy / Q000379:methods*; D002245:Carbon Dioxide / Q000494:pharmacology* / Q000627:therapeutic use; D015687:Cell Hypoxia / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D015609:Organotechnetium Compounds; D010091:Oximes; D010100:Oxygen / Q000494:pharmacology* / Q000627:therapeutic use; D010761:Phosphorus Radioisotopes; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology* / Q000627:therapeutic use; D012510:Sarcoma 180 / Q000188:drug therapy / Q000532:radiotherapy*
chemical_list: D015609:Organotechnetium Compounds; D010091:Oximes; D010761:Phosphorus Radioisotopes; D011838:Radiation-Sensitizing Agents; C105527:technetium Tc 99m 4,9-diaza-3,3,10,10-tetramethyldodecan-2,11-dione dioxime; D002245:Carbon Dioxide; C011700:carbogen; D010100:Oxygen