title: Assessing patient characteristics and radiation-induced non-targeted effects in vivo for high dose-rate (HDR) brachytherapy.
abstract: OBJECTIVE
  To test whether blood, urine, and tissue based colony-forming assays are a useful clinical detection tool for assessing fractionated treatment responses and non-targeted radiation effects in bystander cells.
  
  
  METHODS
  To assess patients' responses to radiation treatments, blood serum, urine, and an esophagus explant-based in vivo colony-forming assay were used from oesophageal carcinoma patients. These patients underwent three fractions of high dose rate (HDR) intraluminal brachytherapy (ILBT).
  
  
  RESULTS
  Human keratinocyte reporters exposed to blood sera taken after the third fraction of brachytherapy had a significant increase in cloning efficiency compared to baseline samples (p < 0.001). Such results may suggest an induced radioresistance response in bystander cells. The data also revealed a clear inverse dose-rate effect during late treatment fractions for the blood sera data only. Patient characteristics such as gender had no statistically significant effect (p > 0.05). Large variability was observed among the patients' tissue samples, these colony-forming assays showed no significant changes throughout fractionated brachytherapy (p > 0.05).
  
  
  CONCLUSIONS
  Large inter-patient variability was found in the urine and tissue based assays, so these techniques were discontinued. However, the simple blood-based assay had much less variability. This technique may have future applications as a biological dosimeter to predict treatment outcome and assess non-targeted radiation effects.
authors.affiliation: a Department of Medical Physics & Applied Radiation Sciences , McMaster University , Hamilton , ON , Canada.
authors.forename: Christine
authors.initials: C
authors.lastname: Pinho
authors.affiliation: a Department of Medical Physics & Applied Radiation Sciences , McMaster University , Hamilton , ON , Canada.
authors.forename: Emilia
authors.initials: E
authors.lastname: Timotin
authors.affiliation: b Department of Oncology , McMaster University , Hamilton , ON , Canada.
authors.forename: Raimond
authors.initials: R
authors.lastname: Wong
authors.affiliation: b Department of Oncology , McMaster University , Hamilton , ON , Canada.
authors.forename: Ranjan K
authors.initials: RK
authors.lastname: Sur
authors.affiliation: a Department of Medical Physics & Applied Radiation Sciences , McMaster University , Hamilton , ON , Canada.|c Department of Radiology , McMaster University , Hamilton , ON , Canada.
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Hayward
authors.affiliation: a Department of Medical Physics & Applied Radiation Sciences , McMaster University , Hamilton , ON , Canada.|c Department of Radiology , McMaster University , Hamilton , ON , Canada.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Farrell
authors.affiliation: a Department of Medical Physics & Applied Radiation Sciences , McMaster University , Hamilton , ON , Canada.
authors.forename: Colin
authors.initials: C
authors.lastname: Seymour
authors.affiliation: a Department of Medical Physics & Applied Radiation Sciences , McMaster University , Hamilton , ON , Canada.
authors.forename: Carmel
authors.initials: C
authors.lastname: Mothersill
mesh_terms: D000368:Aged; D001918:Brachytherapy / Q000009:adverse effects*; D024201:Bystander Effect / Q000528:radiation effects*; D019583:Dose Fractionation, Radiation; D004938:Esophageal Neoplasms / Q000473:pathology / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008297:Male; D011832:Radiation Injuries / Q000097:blood / Q000652:urine
keywords: Bystander effect; blood; esophageal carcinoma; esophageal explants; high dose-rate (HDR) brachytherapy; urine