title: Risk factors for PSA bounce following radiotherapy: outcomes from a multi-modal therapy analysis.
abstract: BACKGROUND
  To identify risk factors for PSA bounce (PSAb) and compare characteristics of prostate cancer patients treated with brachytherapy and external beam radiotherapy (EBRT).
  
  
  METHODS
  We identified 362 patients treated for low risk prostate adenocarcinoma (D'Amico criteria) with a follow up time of at least 36 months. Patients received either: 1) EBRT 76 Gy in 38 fractions (n = 58); 2) hypofractionated EBRT, 45 Gy in 9 once-weekly fractions (n = 74); 3) seed brachytherapy (n = 230). PSAb was defined as a rise >= 0.2 ng/mL with subsequent return to baseline within the first 3 years after treatment. Univariate and multivariate logistic regression models were estimated to assess the association between clinical factors and occurrence of PSAb.
  
  
  RESULTS
  There was no significant difference between treatment groups (p = 0.349), with an overall PSAb rate of 28.5%. Upon univariate analysis, the following were predictive of a lower PSAb rate: older age (OR = 0.96), higher PSA at diagnosis (OR = 0.87), more positive biopsy cores (OR = 0.98), and a higher Cancer of the Prostate Risk Assessment (CAPRA) score (CAPRA of 3 versus 1: OR = 0.33). Multivariate analysis confirmed the significance of fewer positive biopsy cores (OR = 0.99) and a lower CAPRA score (CAPRA 3 versus 1: OR = 0.34). These factors also predicted a shorter time to first PSAb.
  
  
  CONCLUSIONS
  We found comparable rates of PSAb after different regimens of radiotherapy. We hypothesize that it results from late damage to healthy prostatic tissue. This idea is supported by the fact that we found that clinical factors indicative of a lower tumor burden were predictive of a PSAb.
authors.affiliation: Departement of Radiation Oncology, Centre Hospitalier de l'Université de Montréal (CHUM), Hôpital Notre-Dame, Montreal, Quebec, Canada.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Waters
authors.forename: Guila
authors.initials: G
authors.lastname: Delouya
authors.forename: David
authors.initials: D
authors.lastname: Donath
authors.forename: Carole
authors.initials: C
authors.lastname: Lambert
authors.forename: Sandra
authors.initials: S
authors.lastname: Larrivée
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Zorn
authors.forename: Daniel
authors.initials: D
authors.lastname: Taussky
mesh_terms: D000230:Adenocarcinoma / Q000532:radiotherapy*; D000367:Age Factors; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001706:Biopsy; D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011467:Prostate / Q000473:pathology; D017430:Prostate-Specific Antigen / Q000378:metabolism*; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011878:Radiotherapy / Q000379:methods*; D012307:Risk Factors; D016896:Treatment Outcome; D015854:Up-Regulation
chemical_list: D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen