title: Comparison of genitourinary and gastrointestinal toxicity among four radiotherapy modalities for prostate cancer: Conventional radiotherapy, intensity-modulated radiotherapy, and permanent iodine-125 implantation with or without external beam radiotherapy.
abstract: OBJECTIVE
  To compare late genitourinary (GU) and gastrointestinal (GI) toxicity following different prostate cancer treatment modalities.
  
  
  METHODS
  This study included 1084 consecutive prostate cancer patients treated with conventional radiotherapy, intensity-modulated radiotherapy (IMRT), permanent iodine-125 implantation (PI) alone, and PI combined with external beam radiotherapy (PI+EBRT). The effects of treatment- and patient-related factors on late grade ⩾ 2 (G2+) GU/GI toxicity risk were assessed.
  
  
  RESULTS
  The median follow-up was 43 months (range, 12-97 months). Compared to the PI+EBRT, there was significantly less G2+ GU toxicity in the conventional radiotherapy (hazard ratio [HR] = 0.39; 95% CI, 0.20-0.77) and the IMRT (HR=0.45, 95% CI, 0.27-0.73). Compared to the PI+EBRT, there was significantly more G2+ GI toxicity in the IMRT (HR = 2.38; 95% CI, 1.16-4.87). In PI-related groups, prostate equivalent dose in 2 Gy fractions was a significant predictor of G2+ GU toxicity (p = 0.001), and the rectal volume receiving more than 100% of the prescribed dose was a significant predictor of G2+ GI toxicity (p = 0.001).
  
  
  CONCLUSIONS
  The differences in the late G2+ GU/GI risk cannot be explained by the differences in treatment modalities themselves, but by the total radiation dose to the GU/GI tract, which had a causal role in the development of late G2+ GU/GI toxicity across all treatment modality groups.
authors: Department of Radiology, Keio University School of Medicine, Japan.
authors: Shinya
authors: S
authors: Sutani
authors: Department of Radiology, Keio University School of Medicine, Japan; Department of Radiology, National Hospital Organization Saitama Hospital, Japan. Electronic address: ohashi@rad.med.keio.ac.jp.
authors: Toshio
authors: T
authors: Ohashi
authors: Department of Radiology, Keio University School of Medicine, Japan.
authors: Masanori
authors: M
authors: Sakayori
authors: Department of Radiology, Keio University School of Medicine, Japan.
authors: Tomoya
authors: T
authors: Kaneda
authors: Department of Radiology, National Hospital Organization Saitama Hospital, Japan.
authors: Shoji
authors: S
authors: Yamashita
authors: Department of Urology, National Hospital Organization Saitama Hospital, Japan.
authors: Tetsuo
authors: T
authors: Momma
authors: Department of Radiology, Keio University School of Medicine, Japan.
authors: Takashi
authors: T
authors: Hanada
authors: Department of Radiology, Keio University School of Medicine, Japan.
authors: Yutaka
authors: Y
authors: Shiraishi
authors: Department of Radiology, Keio University School of Medicine, Japan.
authors: Junichi
authors: J
authors: Fukada
authors: Department of Urology, Keio University School of Medicine, Japan.
authors: Mototsugu
authors: M
authors: Oya
authors: Department of Radiology, Keio University School of Medicine, Japan.
authors: Naoyuki
authors: N
authors: Shigematsu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy / Q000009:adverse effects* / Q000379:methods; D005500:Follow-Up Studies; D005767:Gastrointestinal Diseases / Q000209:etiology*; D041981:Gastrointestinal Tract / Q000528:radiation effects; D006801:Humans; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D052801:Male Urogenital Diseases / Q000209:etiology*; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011832:Radiation Injuries / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods; D012189:Retrospective Studies; D014566:Urogenital System / Q000528:radiation effects
chemical_list: D007457:Iodine Radioisotopes
keywords: Brachytherapy; IMRT; Prostate cancer; Radiotherapy; Toxicity