title: Chromosome damage and cell proliferation rates in in vitro irradiated whole blood as markers of late radiation toxicity after radiation therapy to the prostate.
abstract: OBJECTIVE
  In vitro irradiated blood samples from prostate cancer patients showing late normal tissue damage were examined for lymphocyte response by measuring chromosomal aberrations and proliferation rate.
  
  
  METHODS
  Patients were selected from a randomized trial evaluating the optimal timing of dose-escalated radiation and short-course androgen deprivation therapy. Of 438 patients, 3% experienced grade 3 late radiation proctitis and were considered to be radiosensitive. Blood samples were taken from 10 of these patients along with 20 matched samples from patients with grade 0 proctitis. The samples were irradiated at 6 Gy and, along with control samples, were analyzed for dicentric chromosomes and excess fragments per cell. Cells in first and second metaphase were also enumerated to determine the lymphocyte proliferation rate.
  
  
  RESULTS
  At 6 Gy, there were statistically significant differences between the radiosensitive and control cohorts for 3 endpoints: the mean number of dicentric chromosomes per cell (3.26 ± 0.31, 2.91 ± 0.32; P=.0258), the mean number of excess fragments per cell (2.27 ± 0.23, 1.43 ± 0.37; P<.0001), and the proportion of cells in second metaphase (0.27 ± 0.10, 0.46 ± 0.09; P=.0007).
  
  
  CONCLUSIONS
  These results may be a valuable indicator for identifying radiosensitive patients and for tailoring radiation therapy.
authors.affiliation: Environmental and Radiation Health Sciences Directorate, Health Canada, Ottawa, ON, Canada. Lindsay.Beaton@hc-sc.gc.ca
authors.forename: Lindsay A
authors.initials: LA
authors.lastname: Beaton
authors.forename: Catherine
authors.initials: C
authors.lastname: Ferrarotto
authors.forename: Leonora
authors.initials: L
authors.lastname: Marro
authors.forename: Sara
authors.initials: S
authors.lastname: Samiee
authors.forename: Shawn
authors.initials: S
authors.lastname: Malone
authors.forename: Scott
authors.initials: S
authors.lastname: Grimes
authors.forename: Kyle
authors.initials: K
authors.lastname: Malone
authors.forename: Ruth C
authors.initials: RC
authors.lastname: Wilkins
mesh_terms: D000368:Aged; D049109:Cell Proliferation / Q000528:radiation effects*; D002869:Chromosome Aberrations; D005819:Genetic Markers / Q000235:genetics; D006801:Humans; D008214:Lymphocytes / Q000473:pathology / Q000528:radiation effects*; D008297:Male; D008677:Metaphase / Q000235:genetics; D008875:Middle Aged; D011349:Proctitis / Q000097:blood* / Q000209:etiology; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000097:blood / Q000235:genetics / Q000473:pathology / Q000532:radiotherapy*; D011829:Radiation Dosage; D011832:Radiation Injuries / Q000235:genetics* / Q000473:pathology*; D011836:Radiation Tolerance / Q000235:genetics*
chemical_list: D005819:Genetic Markers