title: Experimental model of ultrasound thermotherapy in rats inoculated with Walker-236 tumor.
abstract: OBJECTIVE
  To develop a model to evaluate the effects of focal pulsed ultrasound (US) waves as a source of heat for treatment of murine subcutaneous implanted Walker tumor.
  
  
  METHODS
  An experimental, controlled, comparative study was conducted. Twenty male Wistar rats (160-300 g) randomized in 2 equal groups (G-1: Control and G-2: Hyperthermia) were inoculated with Walker-256 carcinosarcoma tumor. After 5 days G-2 rats were submitted to 45ºC hyperthermia. Heat was delivered directly to the tumor by an ultrasound (US) equipment (3 MHz frequency, 1,5W/cm³). Tumor temperature reached 45º C in 3 minutes and was maintained at this level for 5 minutes. Tumor volume was measured on days 5, 8, 11, 14 e 17 post inoculation in both groups. Unpaired t-test was used for comparison. P<0.05 was considered significant.
  
  
  RESULTS
  Tumor volume was significantly greater in day 5 and decreased in days 11, 14 and 17 in treated rats. Rats treated with hyperthermia survived longer than control animals. On the 29th day following tumor inoculation, 40% of control rats and 77.78% of hyperthermia-treated rats remained alive.
  
  
  CONCLUSIONS
  The proposed model is quite simple and may be used in less sophisticated laboratory settings for studying the effects of focal hyperthermia in the treatment of malignant implanted tumours or in survival studies.
authors.affiliation: Department of Surgery, Federal University of Ceara, Fortaleza-CE, Brazil.
authors.forename: José Antonio Carlos Otaviano David
authors.initials: JA
authors.lastname: Morano
authors.forename: Naylana
authors.initials: N
authors.lastname: Cordeiro
authors.forename: Sergio Botelho
authors.initials: SB
authors.lastname: Guimarães
authors.forename: Francisco Vagnaldo Fechine
authors.initials: FV
authors.lastname: Jamacaru
authors.forename: Manoel Odorico de
authors.initials: MO
authors.lastname: Moraes Filho
mesh_terms: D000818:Animals; D002279:Carcinoma 256, Walker / Q000473:pathology / Q000628:therapy*; D004195:Disease Models, Animal; D006979:Hyperthermia, Induced / Q000379:methods*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D016019:Survival Analysis; D013696:Temperature; D013997:Time Factors; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000379:methods*