title: PSA nadir of <0.5 ng/mL following brachytherapy for early-stage prostate adenocarcinoma is associated with freedom from prostate-specific antigen failure.
abstract: OBJECTIVE
  Because limited information exists regarding whether the rate or magnitude of PSA decline following brachytherapy predicts long-term clinical outcomes, we evaluated whether achieving a prostate-specific antigen (PSA) nadir (nPSA) <0.5 ng/mL following brachytherapy is associated with decreased PSA failure and/or distant metastasis.
  
  
  METHODS
  We retrospectively analyzed our database of early-stage prostate adenocarcinoma patients who underwent brachytherapy, excluding those receiving androgen-deprivation therapy and those with <2 years follow-up. Median and mean pretreatment PSA were 6 ng/mL and 7.16 ng/mL, respectively. By clinical stage, 775 were low risk (≤ T2a), 126 were intermediate risk (T2b), and 20 were high risk (>T2b). By Gleason score, 840 were low risk (≤ 6), 71 were intermediate risk (7), and 10 were high risk (>7). Patients were treated with brachytherapy only (I-125, n = 779, or Pd-103, n = 47), or brachytherapy + external-beam radiation therapy (n = 95). Median follow-up was 6.3 years. We noted whether nPSA <0.5 ng/mL was achieved and the time to achieve this nadir and tested for associations with pretreatment risk factors. We also determined whether this PSA endpoint was associated with decreased PSA failure or distant metastasis.
  
  
  RESULTS
  Absence of high-risk factors in clinical stage (≤ T2b), Gleason score (≤ 7), and pretreatment PSA (≤ 20 ng/mL) was significantly associated with achieving nPSA <0.5 ng/mL. By Kaplan-Meier analysis, patients achieving nPSA <0.5 ng/mL had significantly higher long-term freedom from biochemical failure (FFBF) than nonresponders (5-year FFBF: 95.2 ± 0.8% vs. 71.5 ± 6.7%; p < 0.0005). Among responders, those who achieved nPSA <0.5 ng/mL in ≤ 5 years had higher FFBF than those requiring >5 years (5-year FFBF: 96.7 ± 0.7% vs. 80.8 ± 4.6%; p < 0.0005). On multivariate analysis, patients who achieved nPSA <0.5 ng/mL in ≤ 5 years had significantly higher FFBF than other patients.
  
  
  CONCLUSIONS
  Pretreatment risk factors (clinical tumor stage, Gleason score, pretreatment PSA) strongly predict for patients achieving nPSA <0.5 ng/mL following brachytherapy, and this cohort had significantly higher long-term FFBF.
authors: Department of Radiation Oncology, Mount Sinai Medical Center, New York, NY 10029, USA. Richard.Stock@mountsinai.org
authors: Eric C
authors: EC
authors: Ko
authors: Nelson N
authors: NN
authors: Stone
authors: Richard G
authors: RG
authors: Stock
mesh_terms: D000230:Adenocarcinoma / Q000097:blood* / Q000473:pathology / Q000532:radiotherapy* / Q000556:secondary; D000368:Aged; D000704:Analysis of Variance; D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D010165:Palladium / Q000627:therapeutic use; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology / Q000532:radiotherapy*; D011868:Radioisotopes / Q000627:therapeutic use; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D012016:Reference Values; D012189:Retrospective Studies; D012306:Risk
chemical_list: D007457:Iodine Radioisotopes; D011868:Radioisotopes; D010165:Palladium; D017430:Prostate-Specific Antigen