title: Permanent interstitial low-dose-rate brachytherapy for patients with low risk prostate cancer: An interim analysis of 312 cases.
abstract: OBJECTIVE
  The biochemical relapse-free survival (bRFS) rate after treatment with permanent iodine-125 seed implantation (PSI) or combined seeds and external beam radiotherapy (COMB) for clinical stage T1-T2 localized prostate cancer is a clinically relevant endpoint. The goal of this work was to evaluate the influence of relevant patient- and treatment-related factors.
  
  
  METHODS
  The study population comprised 312 consecutive patients treated with permanent seed implantation. All patients were evaluable for analysis of overall survival (OS) and disease-specific survival (DSS), 230 for bRFS, of which 192 were in the PSI group and 38 in the COMB group. The prescribed minimum peripheral dose was 145 Gy for PSI, for COMB 110 Gy implant and external beam radiotherapy of 45 Gy. The median follow-up time was 33 months (range 8-66 months). bRFS was defined as a serum prostate-specific antigen (PSA) level ≤ 0.2 ng/ml at last follow-up.
  
  
  RESULTS
  Overall, the actuarial bRFS at 50 months was 88.4 %. The 50-month bRFS rate for PSI and COMB was 90.9 %, and 77.2 %, respectively. In the univariate analysis, age in the categories ≤ 63 and > 63 years (p < 0.00), PSA nadir (≤ 0.5 ng/ml and > 0.5 ng\ml) and PSA bounce (yes/no) were the significant predicting factors for bRFS. None of the other patient and treatment variables (treatment modality, stage, PSA, Gleason score, risk group, number of risk factors, D90 and various other dose parameters) were found to be a statistically significant predictor of 50-month bRFS.
  
  
  CONCLUSIONS
  The biochemical failure rates were low in this study. As a proof of principle, our large monocenteric analysis shows that low-dose-rate brachytherapy is an effective and safe procedure for patients with early stage prostate cancer.
authors.affiliation: Department for Radiation Oncology of Charité School of Medicine, University Hospital Berlin, Augustenburger Platz 1, 13353, Berlin, Germany, Harun.Badakhshi@charite.de.
authors.forename: Harun
authors.initials: H
authors.lastname: Badakhshi
authors.forename: Reinhold
authors.initials: R
authors.lastname: Graf
authors.forename: Volker
authors.initials: V
authors.lastname: Budach
authors.forename: Peter
authors.initials: P
authors.lastname: Wust
mesh_terms: D017677:Age Distribution; D000368:Aged; D001918:Brachytherapy / Q000295:instrumentation* / Q000379:methods / Q000401:mortality*; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D005858:Germany; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000401:mortality* / Q000517:prevention & control*; D015995:Prevalence; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000401:mortality* / Q000532:radiotherapy*; D018570:Risk Assessment; D015996:Survival Rate; D016896:Treatment Outcome