title: Prostate-specific antigen nadir after high-dose-rate brachytherapy predicts long-term survival outcomes in high-risk prostate cancer.
abstract: OBJECTIVE
  To evaluate the prognostic value of prostate-specific antigen nadir (nPSA) after high-dose-rate (HDR) brachytherapy in clinically non-metastatic high-risk prostate cancer patients.
  
  
  METHODS
  Data from 216 patients with high-risk or locally advanced prostate cancer who underwent HDR brachytherapy and external beam radiation therapy with long-term androgen deprivation therapy (ADT) between 2003 and 2008 were analyzed. The median prostate-specific antigen (PSA) level at diagnosis was 24 ng/ml (range: 3-338 ng/ml). The clinical stage was T1c-2a in 55 cases (26%), T2b-2c in 48 (22%), T3a in 75 (35%), and T3b-4 in 38 (17%). The mean dose to 90% of the planning target volume was 6.3 Gy/fraction of HDR brachytherapy. After 5 fractions, external beam radiation therapy with 10 fractions of 3 Gy was administered. All patients initially underwent neoadjuvant ADT for at least 6 months, and adjuvant ADT was continued for 36 months. The median follow-up was 7 years from the start of radiotherapy.
  
  
  RESULTS
  The 7-year PSA relapse-free rate among patients with a post-radiotherapy nPSA level of ≤ 0.02 ng/ml was 94%, compared with 23% for patients with higher nPSA values (HR = 28.57; 95% CI: 12.04-66.66; p < 0.001). Multivariate analysis revealed that the nPSA value after radiotherapy was a significant independent predictor of biochemical failure, whereas pretreatment predictive values for worse biochemical control including higher level of initial PSA, Gleason score ≥ 8, positive biopsy core rate ≥ 67%, and T3b-T4, failed to reach independent predictor status. The 7-year cancer-specific survival rate among patients with a post-radiotherapy nPSA level of ≤ 0.02 ng/ml was 99%, compared with 82% for patients with higher nPSA values (HR = 32.25; 95% CI: 3.401-333.3; p = 0.002).
  
  
  CONCLUSIONS
  A post-radiotherapy nPSA value of ≤ 0.02 ng/ml was associated with better long-term biochemical tumor control even if patients had pretreatment predictive values for worse control.
authors.affiliation: Department of Urology.
authors.forename: Hideyasu
authors.initials: H
authors.lastname: Tsumura
authors.affiliation: Department of Urology.
authors.forename: Takefumi
authors.initials: T
authors.lastname: Satoh
authors.affiliation: Department of Radiology and Radiation Oncology, Kitasato University School of Medicine, Sagamihara, Japan.
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Ishiyama
authors.affiliation: Department of Urology.
authors.forename: Ken-Ichi
authors.initials: K
authors.lastname: Tabata
authors.affiliation: Department of Radiology and Radiation Oncology, Kitasato University School of Medicine, Sagamihara, Japan.
authors.forename: Shouko
authors.initials: S
authors.lastname: Komori
authors.affiliation: Department of Radiology and Radiation Oncology, Kitasato University School of Medicine, Sagamihara, Japan.
authors.forename: Akane
authors.initials: A
authors.lastname: Sekiguchi
authors.affiliation: Department of Urology.
authors.forename: Masaomi
authors.initials: M
authors.lastname: Ikeda
authors.affiliation: Department of Urology.
authors.forename: Shinji
authors.initials: S
authors.lastname: Kurosaka
authors.affiliation: Department of Urology.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Fujita
authors.affiliation: Department of Radiology and Radiation Oncology, Kitasato University School of Medicine, Sagamihara, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kitano
authors.affiliation: Department of Radiology and Radiation Oncology, Kitasato University School of Medicine, Sagamihara, Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Hayakawa
authors.affiliation: Department of Urology.
authors.forename: Masatsugu
authors.initials: M
authors.lastname: Iwamura
keywords: PSA nadir; brachytherapy; high-dose-rate; prostate cancer