title: Mid-term outcome of permanent prostate iodine-125 brachytherapy in Japanese patients.
abstract: OBJECTIVE
  To analyze mid-term oncological outcomes of low-dose rate brachytherapy in Japanese patients.
  
  
  METHODS
  Between 2003 and 2010, 604 consecutive patients with clinically localized prostate cancer were treated with low-dose rate brachytherapy at Jikei University Hospital in Tokyo, Japan. Median follow up was 48 months. Of these patients, 260 (43%) were treated with neoadjuvant therapy, 45 (7.5%) with adjuvant hormonal therapy and 75 (12.4%) with supplemental external beam radiation therapy. Biochemical recurrence was defined as the prostate-specific antigen nadir plus 2 ng/mL.
  
  
  RESULTS
  Of the 604 patients, 219 (36.2%) were low risk, 361 (59.8%) were intermediate risk and 24 (4.0%) had high-risk disease. The median biologically effective dose was 174.4 Gy2. At 8 years, biochemical recurrence-free survival, cancer-specific survival, and overall survival were 82.2%, 100% and 95.6%, respectively. Biochemical recurrence-free survival at 8 years was 89.9%, 79.4% and 52.5%, for the low-, intermediate-, and high-risk groups, respectively. Biochemical recurrence-free survival for the high-risk group was significantly lower than the low- and intermediate-risk groups (P < 0.001). Biochemical recurrence-free survival did not differ significantly by biologically effective dose stratification. In multivariate analysis, younger age (P = 0.045), higher prostate-specific antigen (P = 0.004), higher Gleason score (P = 0.006) and higher clinical T stage (P = 0.008) were significant covariates associated with biochemical recurrence. The addition of hormonal therapy or external beam radiation therapy was associated with significantly better outcomes than low-dose rate brachytherapy monotherapy (P = 0.0021 and 0.010). Just four patients experienced G3 genitourinary or gastrointestinal toxicity.
  
  
  CONCLUSIONS
  Low-dose rate brachytherapy results in excellent mid-term oncological outcomes and acceptable toxicity in Japanese patients. In our experience, biologically effective dose does not represent a significant predictor for biochemical recurrence.
authors.affiliation: Department of Urology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kimura
authors.forename: Masahito
authors.initials: M
authors.lastname: Kido
authors.forename: Kenta
authors.initials: K
authors.lastname: Miki
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sasaki
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Kuruma
authors.forename: Norihiro
authors.initials: N
authors.lastname: Hayashi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takahashi
authors.forename: Manabu
authors.initials: M
authors.lastname: Aoki
authors.forename: Shin
authors.initials: S
authors.lastname: Egawa
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People; D001918:Brachytherapy / Q000379:methods*; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D007457:Iodine Radioisotopes
keywords: Japanese patients; low-dose rate brachytherapy; prostate cancer