title: Role of isotope selection in long-term outcomes in patients with intermediate-risk prostate cancer treated with a combination of external beam radiotherapy and low-dose-rate interstitial brachytherapy.
abstract: OBJECTIVE
  To examine the rates of long-term biochemical recurrence-free survival (BRFS) with respect to isotope in intermediate-risk prostate cancer treated with external beam radiotherapy (EBRT) and brachytherapy.
  
  
  METHODS
  A total of 242 consecutive patients with intermediate-risk prostate cancer were treated with iodine-125 ((125)I) or palladium-103 ((103)Pd) implants after EBRT (range 45.0-50.4 Gy) from 1996 to 2002. Of the 242 patients, 119 (49.2%) were treated with (125)I and 123 (50.8%) with (103)Pd. Multivariate Cox regression analysis was used to analyze BRFS, defined according to the Phoenix definition (prostate-specific antigen nadir plus 2 ng/mL) with respect to Gleason score, stage, pretreatment prostate-specific antigen level, and source selection. Late genitourinary/gastrointestinal toxicities were assessed using the Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer scale.
  
  
  RESULTS
  At a median follow-up of 10 years, the BRFS rate was 77.3%. A statistically significant difference was found in the 10-year BRFS rate between the (125)I- and (103)Pd-treated groups (82.7% and 70.6%, respectively; P = .001). The addition of hormonal therapy did not improve the 10-year BRFS rate (77.6%) compared with RT alone (77.1%; P = .22). However, a statistically significant difference in the BRFS rate was found with the addition of hormonal therapy to (103)Pd, improving the 10-year BRFS rate for (73.8%) compared with (103)Pd alone (69.1%; P = .008). On multivariate analysis, isotope type ((103)Pd vs (125)I), pretreatment prostate-specific antigen level >10 ng/mL, and greater tumor stage increased the risk of recurrence by 2.6-fold (P = .007), 5.9-fold (P < .0001), and 1.7-fold (P = .14), respectively.
  
  
  CONCLUSIONS
  (125)I renders a superior rate of BRFS compared with (103)Pd when used with EBRT. Hormonal therapy does not provide additional benefit in patients with intermediate-risk prostate cancer treated with a combination of EBRT and brachytherapy, except for the addition of hormonal therapy to (103)Pd.
authors.affiliation: Department of Radiation Oncology, Weill Medical College of Cornell University, New York, New York 10065, USA. gaw9008@med.cornell.edu
authors.forename: A Gabriella
authors.initials: AG
authors.lastname: Wernicke
authors.forename: Michael
authors.initials: M
authors.lastname: Shamis
authors.forename: Weisi
authors.initials: W
authors.lastname: Yan
authors.forename: Samuel
authors.initials: S
authors.lastname: Trichter
authors.forename: Albert M
authors.initials: AM
authors.lastname: Sabbas
authors.forename: Yevgenia
authors.initials: Y
authors.lastname: Goltser
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Christos
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Brennan
authors.forename: Bhupesh
authors.initials: B
authors.lastname: Parashar
authors.forename: Dattatreyudu
authors.initials: D
authors.lastname: Nori
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D006728:Hormones / Q000627:therapeutic use; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D009367:Neoplasm Staging; D010165:Palladium / Q000627:therapeutic use*; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000532:radiotherapy*; D011868:Radioisotopes / Q000627:therapeutic use; D050397:Radiotherapy, Intensity-Modulated; D012307:Risk Factors
chemical_list: D006728:Hormones; D007457:Iodine Radioisotopes; D011868:Radioisotopes; D010165:Palladium; D017430:Prostate-Specific Antigen