title: Long-term outcomes from a prospective trial of stereotactic body radiotherapy for low-risk prostate cancer.
abstract: OBJECTIVE
  Hypofractionated radiotherapy has an intrinsically different normal tissue and tumor radiobiology. The results of a prospective trial of stereotactic body radiotherapy (SBRT) for prostate cancer with long-term patient-reported toxicity and tumor control rates are presented.
  
  
  METHODS
  From 2003 through 2009, 67 patients with clinically localized low-risk prostate cancer were enrolled. Treatment consisted of 36.25 Gy in 5 fractions using SBRT with the CyberKnife as the delivery technology. No patient received hormone therapy. Patient self-reported bladder and rectal toxicities were graded on the Radiation Therapy Oncology Group scale (RTOG).
  
  
  RESULTS
  Median follow-up was 2.7 years. There were no grade 4 toxicities. Radiation Therapy Oncology Group Grade 3, 2, and 1 bladder toxicities were seen in 3% (2 patients), 5% (3 patients), and 23% (13 patients) respectively. Dysuria exacerbated by urologic instrumentation accounted for both patients with Grade 3 toxicity. Urinary incontinence, complete obstruction, or persistent hematuria was not observed. Rectal Grade 3, 2, and 1 toxicities were seen in 0, 2% (1 patient), and 12.5% (7 patients), respectively. Persistent rectal bleeding was not observed. Low-grade toxicities were substantially less frequent with QOD vs. QD dose regimen (p = 0.001 for gastrointestinal and p = 0.007 for genitourinary). There were two prostate-specific antigen (PSA), biopsy-proven failures with negative metastatic workup. Median PSA at follow-up was 0.5 ± 0.72 ng/mL. The 4-year Kaplan-Meier PSA relapse-free survival was 94% (95% confidence interval, 85%-102%).
  
  
  CONCLUSIONS
  Significant late bladder and rectal toxicities from SBRT for prostate cancer are infrequent. PSA relapse-free survival compares favorably with other definitive treatments. The current evidence supports consideration of stereotactic body radiotherapy among the therapeutic options for localized prostate cancer.
authors.affiliation: Departments of Radiation Oncology, University of California Los Angeles School of Medicine, Los Angeles, CA 90095, USA. crking@mednet.ucla.edu
authors.forename: Christopher R
authors.initials: CR
authors.lastname: King
authors.forename: James D
authors.initials: JD
authors.lastname: Brooks
authors.forename: Harcharan
authors.initials: H
authors.lastname: Gill
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Presti
mesh_terms: D000368:Aged; D019583:Dose Fractionation, Radiation; D006801:Humans; D008297:Male; D011446:Prospective Studies; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000473:pathology / Q000601:surgery*; D011832:Radiation Injuries / Q000150:complications* / Q000473:pathology; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D012007:Rectum / Q000528:radiation effects*; D016896:Treatment Outcome; D001743:Urinary Bladder / Q000528:radiation effects*; D014555:Urination Disorders
chemical_list: D017430:Prostate-Specific Antigen