title: Analysis of biochemical control and prognostic factors in patients treated with either low-dose three-dimensional conformal radiation therapy or high-dose intensity-modulated radiotherapy for localized prostate cancer.
abstract: OBJECTIVE
  To identify prognostic factors and evaluate biochemical control rates for patients with localized prostate cancer treated with either high-dose intensity-modulated radiotherapy (IMRT) or conventional-dose three-dimensional conformal radiotherapy 3D-CRT.
  
  
  METHODS
  Four hundred sixteen patients with a minimum follow-up of 3 years (median, 5 years) were included. Two hundred seventy-one patients received 3D-CRT with a median dose of 68.4 Gy (range, 66-71 Gy). The next 145 patients received IMRT with a median dose of 75.6 Gy (range, 70.2-77.4 Gy). Biochemical control rates were calculated according to both American Society for Therapeutic Radiology and Oncology (ASTRO) consensus definitions. Prognostic factors were identified using both univariate and multivariate analyses.
  
  
  RESULTS
  The 5-year biochemical control rate was 60.4% for 3D-CRT and 74.1% for IMRT (p < 0.0001, first ASTRO Consensus definition). Using the ASTRO Phoenix definition, the 5-year biochemical control rate was 74.4% and 84.6% with 3D-RT and IMRT, respectively (p = 0.0326). Univariate analyses determined that PSA level, T stage, Gleason score, perineural invasion, and radiation dose were predictive of biochemical control. On multivariate analysis, dose, Gleason score, and perineural invasion remained significant.
  
  
  CONCLUSIONS
  On the basis of both ASTRO definitions, dose, Gleason score, and perineural invasion were predictive of biochemical control. Intensity-modulated radiotherapy allowed delivery of higher doses of radiation with very low toxicity, resulting in improved biochemical control.
authors.affiliation: Department of Radiation Oncology, Mayo Clinic Scottsdale, 13400 E. Shea Boulevard, Scottsdale, AZ 85259, USA. vora.sujay@mayo.edu
authors.forename: Sujay A
authors.initials: SA
authors.lastname: Vora
authors.forename: William W
authors.initials: WW
authors.lastname: Wong
authors.forename: Steven E
authors.initials: SE
authors.lastname: Schild
authors.forename: Gary A
authors.initials: GA
authors.lastname: Ezzell
authors.forename: Michele Y
authors.initials: MY
authors.lastname: Halyard
mesh_terms: D000704:Analysis of Variance; D032921:Consensus; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood* / Q000473:pathology / Q000532:radiotherapy*; D018787:Radiation Oncology / Q000592:standards; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods
chemical_list: D017430:Prostate-Specific Antigen