title: Effect of fractionated radiotherapy on the parotid gland: an experimental study in Brazilian minipigs.
abstract: BACKGROUND
  Radiotherapy (RT) of head and neck neoplasms often damages the salivary glands.
  
  
  OBJECTIVE
  To examine the pattern of morphologic changes resulting from RT of the head and neck region in minipig parotid glands in a clinical and experimental research setting.
  
  
  METHODS
  Twelve 18-month-old male Brazilian minipigs weighing 30-40 kg were selected. Eight minipigs were assigned to the experimental group (group 1) and 4 to the control group (group 2). The RT was performed under general anesthesia at Erasto Gaertner Hospital, Curitiba, Brazil, using an á/â ratio of 2.5. The minipigs from group 1 underwent 3 sessions of irradiation with Cobalt 60 of the head and neck, bilaterally, with 3 exposures of 8 Gy each at 7-day intervals for a total dose of 24 Gy. The animals were sacrificed 12 weeks post-RT.
  
  
  RESULTS
  The irradiated parotid glands displayed reductions in the size and number of acini as well as loss of secretory granules. The presence of fibrosis and loss of parenchyma relative to non-irradiated glands were observed, with an average reduction in volume of 54%.
  
  
  CONCLUSIONS
  Our results demonstrate that this model for parotid gland damage resulting from an RT regimen appears to be useful for preclinical large animal studies of RT-induced damage and testing novel potential treatment options. Although recent advances in radiation therapy, such as intensity-modulated radiation therapy, have reduced the dose and limited the field of radiation, considerable salivary gland injury still occurs and can greatly impact the patient's quality of life after cancer treatment.
authors.affiliation: DDS, MSc, PhD student. Oral and Maxillofacial Surgery Department, Erasto Gaertner Hospital, Curitiba / PR - Brazil; Oncology Department, University of São Paulo, São Paulo / SP - Brazil.
authors.forename: Roberta Targa
authors.initials: RT
authors.lastname: Stramandinoli-Zanicotti
authors.affiliation: DDS, PhD. Chief of the Oral and Maxillofacial Surgery Department, Erasto Gaertner Hospital, Curitiba / PR - Brazil.
authors.forename: Laurindo Moacir
authors.initials: LM
authors.lastname: Sassi
authors.affiliation: DDS, PhD. Oral and Maxillofacial Surgery Department, Erasto Gaertner Hospital, Curitiba / PR - Brazil.
authors.forename: Juliana Lucena
authors.initials: JL
authors.lastname: Schussel
authors.affiliation: DVM, PhD. Experimental Surgery Department, Positivo University, Curitiba / PR - Brazil; Veterinary Medicine of Federal University of Parana, Curitiba / PR - Brazil.
authors.forename: Maria Fernanda
authors.initials: MF
authors.lastname: Torres
authors.affiliation: Medical Physics. Radiotherapy Department, Erasto Gaertner Hospital, Curitiba / PR - Brazil.
authors.forename: Melissa
authors.initials: M
authors.lastname: Funchal
authors.affiliation: MD. Radiotherapy Department, Erasto Gaertner Hospital, Curitiba / PR - Brazil.
authors.forename: Gustavo Henrique
authors.initials: GH
authors.lastname: Smaniotto
authors.affiliation: DDS. Oral and Maxillofacial Surgery Department, Erasto Gaertner Hospital, Curitiba / PR - Brazil.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Dissenha
authors.affiliation: MD, PhD. Head and Neck Surgery and Otorhinolaryngology Department, Hospital de Cancer de Barretos, Barretos, SP, Brazil; Oncology Department, University of São Paulo, São Paulo / SP - Brazil.
authors.forename: Andre Lopes
authors.initials: AL
authors.lastname: Carvalho
keywords: Head and Neck Neoplasms; Miniature; Radiotherapy; Salivary Glands; Swine; Xerostomia