title: Risk Factors and Time to Occurrence of Genitourinary Toxicity After External Beam Radiotherapy for Prostate Cancer.
abstract: OBJECTIVE
  To retrospectively investigate the risk factors and time to occurrence of genitourinary (GU) toxicity after radiotherapy for localized prostate cancer.
  
  
  METHODS
  The study included 320 patients. The radiotherapy planning target volume encompassed the prostate with a 1-cm margin in the transverse plane and a 1-cm margin (Group A) or a 1.5-cm margin (Group B) in the longitudinal plane. Incidence rates, risk factors and time to occurrence of GU toxicity were evaluated.
  
  
  RESULTS
  After a median follow-up of 38.2 months, the rate of late grade 2-3 GU toxicity was 5.9% and the median interval was 18.3 months. The wider longitudinal margin was the single significant independent factor. The 2-year cumulative incidence rates of late grade ≥2 GU toxicity were 2.8% and 7.5% in Group A and B patients.
  
  
  CONCLUSIONS
  A wider radiotherapy margin increased the risk of GU toxicity and led to earlier occurrence.
authors.affiliation: Department of Radiation Oncology, Niigata Cancer Center Hospital, Niigata, Japan ayae-kanemoto@umin.ac.jp.
authors.forename: Ayae
authors.initials: A
authors.lastname: Kanemoto
authors.affiliation: Department of Radiation Oncology, Niigata Cancer Center Hospital, Niigata, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Matsumoto
authors.affiliation: Department of Radiation Oncology, Niigata Cancer Center Hospital, Niigata, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Sugita
authors.affiliation: Department of Radiation Oncology, Niigata University Medical and Dental Hospital, Niigata, Japan.
authors.forename: Eisuke
authors.initials: E
authors.lastname: Abe
authors.affiliation: Department of Radiation Oncology, Niigata University Medical and Dental Hospital, Niigata, Japan.
authors.forename: Nobuko
authors.initials: N
authors.lastname: Yamana
authors.affiliation: Department of Urology, Niigata Cancer Center Hospital, Niigata, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Saito
authors.affiliation: Department of Urology, Niigata Cancer Center Hospital, Niigata, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kobayashi
authors.affiliation: Department of Urology, Niigata Cancer Center Hospital, Niigata, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamazaki
authors.affiliation: Department of Urology, Niigata Cancer Center Hospital, Niigata, Japan.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Bilim
authors.affiliation: Department of Urology, Niigata Cancer Center Hospital, Niigata, Japan.
authors.forename: Toshiki
authors.initials: T
authors.lastname: Tanikawa
mesh_terms: D000368:Aged; D005837:Genitalia, Male / Q000528:radiation effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011878:Radiotherapy / Q000009:adverse effects; D012307:Risk Factors; D013997:Time Factors; D014551:Urinary Tract / Q000528:radiation effects*; D055815:Young Adult
keywords: Genitourinary toxicity; external-beam radiotherapy; prostate cancer; risk factor; timing