title: Clinical experience with intensity modulated radiation therapy (IMRT) in prostate cancer.
abstract: OBJECTIVE
  To compare acute and late toxicities of high-dose radiation for prostate cancer delivered by either conventional three-dimensional conformal radiation therapy (3D-CRT) or intensity modulated radiation therapy (IMRT).
  
  
  METHODS
  Between September 1992 and February 1998, 61 patients with clinical stage T1c- T3 prostate cancer were treated with 3D-CRT and 171 with IMRT to a prescribed dose of 81 Gy. To quantitatively evaluate the differences between conventional 3D-CRT and IMRT, 20 randomly selected patients were planned concomitantly by both techniques and the resulting treatment plans were compared. Acute and late radiation-induced morbidity was evaluated in all patients and graded according to the Radiation Therapy Oncology Group toxicity scale.
  
  
  RESULTS
  Compared with conventional 3D-CRT, IMRT improved the coverage of the clinical target volume (CTV) by the prescription dose and reduced the volumes of the rectal and bladder walls carried to high dose levels (P<0.01), indicating improved conformality with IMRT. Acute and late urinary toxicities were not significantly different for the two methods. However, the combined rates of acute grade 1 and 2 rectal toxicities and the risk of late grade 2 rectal bleeding were significantly lower in the IMRT patients. The 2-year actuarial risk of grade 2 bleeding was 2% for IMRT and 10% for conventional 3D-CRT (P<0.001).
  
  
  CONCLUSIONS
  The data demonstrate the feasibility and safety of high-dose IMRT for patients with localized prostate cancer and provide a proof-of-principle that this method improves dose conformality relative to tumor coverage and exposure to normal tissues.
authors.affiliation: Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, 1275 York Ave., New York, NY 10021, USA.
authors.forename: M J
authors.initials: MJ
authors.lastname: Zelefsky
authors.forename: Z
authors.initials: Z
authors.lastname: Fuks
authors.forename: L
authors.initials: L
authors.lastname: Happersett
authors.forename: H J
authors.initials: HJ
authors.lastname: Lee
authors.forename: C C
authors.initials: CC
authors.lastname: Ling
authors.forename: C M
authors.initials: CM
authors.lastname: Burman
authors.forename: M
authors.initials: M
authors.lastname: Hunt
authors.forename: T
authors.initials: T
authors.lastname: Wolfe
authors.forename: E S
authors.initials: ES
authors.lastname: Venkatraman
authors.forename: A
authors.initials: A
authors.lastname: Jackson
authors.forename: M
authors.initials: M
authors.lastname: Skwarchuk
authors.forename: S A
authors.initials: SA
authors.lastname: Leibel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005240:Feasibility Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted; D020266:Radiotherapy, Conformal / Q000379:methods* / Q000592:standards; D012449:Safety