title: Rectal bleeding after high-dose-rate brachytherapy combined with hypofractionated external-beam radiotherapy for localized prostate cancer: the relationship between dose-volume histogram parameters and the occurrence rate.
abstract: OBJECTIVE
  To determine the predictive risk factors for Grade 2 or worse rectal bleeding after high-dose-rate brachytherapy (HDR-BT) combined with hypofractionated external-beam radiotherapy (EBRT) for prostate cancer using dose-volume histogram analysis.
  
  
  METHODS
  The records of 216 patients treated with HDR-BT combined with EBRT were analyzed. The treatment protocols for HDR-BT were 5 Gy × five times in 3 days or 7 Gy × three, 10.5 Gy × two, or 9 Gy × two in 2 days. The EBRT doses ranged from 45 to 51 Gy with a fractional dose of 3 Gy.
  
  
  RESULTS
  In 20 patients Grade 2 or worse rectal bleeding developed, and the cumulative incidence rate was 9% at 5 years. By converting the HDR-BT and EBRT radiation doses into biologic effective doses (BED), the BED(3) at rectal volumes of 5% and 10% in the patients who experienced bleeding were significantly higher than those in the remaining 196 patients. Univariate analysis showed that a higher rectal BED(3-5%) and the use of fewer needles in brachytherapy were correlated with the incidence of bleeding, but BED(3-5%) was found to be the only significant factor on multivariate analysis.
  
  
  CONCLUSIONS
  The radiation dose delivered to small rectal lesions as 5% is important for predicting Grade 2 or worse rectal bleeding after HDR-BT combined with EBRT for prostate cancer.
authors.affiliation: Department of Radiation Oncology, Gunma University Graduate School of Medicine, Gunma, Japan. masaoka@showa.gunma-u.ac.jp
authors.forename: Masahiko
authors.initials: M
authors.lastname: Okamoto
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Ebara
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kato
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Tamaki
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Akimoto
authors.forename: Kazuto
authors.initials: K
authors.lastname: Ito
authors.forename: Mai
authors.initials: M
authors.lastname: Miyakubo
authors.forename: Takumi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Suzuki
authors.forename: Takeo
authors.initials: T
authors.lastname: Takahashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakano
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001918:Brachytherapy / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D018572:Disease-Free Survival; D019583:Dose Fractionation, Radiation; D005500:Follow-Up Studies; D006471:Gastrointestinal Hemorrhage / Q000453:epidemiology / Q000209:etiology*; D006801:Humans; D015994:Incidence; D007496:Iridium Radioisotopes / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009339:Needles; D011471:Prostatic Neoplasms / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000150:complications*; D011859:Radiography; D012007:Rectum / Q000000981:diagnostic imaging / Q000528:radiation effects*; D012062:Relative Biological Effectiveness; D012307:Risk Factors; D013997:Time Factors; D047368:Tumor Burden
chemical_list: D007496:Iridium Radioisotopes