title: Phase I dose-escalation study of stereotactic body radiation therapy for low- and intermediate-risk prostate cancer.
abstract: OBJECTIVE
  To evaluate the tolerability of escalating doses of stereotactic body radiation therapy in the treatment of localized prostate cancer.
  
  
  METHODS
  Eligible patients included those with Gleason score 2 to 6 with prostate-specific antigen (PSA) ≤ 20, Gleason score 7 with PSA ≤ 15, ≤ T2b, prostate size ≤ 60 cm(3), and American Urological Association (AUA) score ≤ 15. Pretreatment preparation required an enema and placement of a rectal balloon. Dose-limiting toxicity (DLT) was defined as grade 3 or worse GI/genitourinary (GU) toxicity by Common Terminology Criteria of Adverse Events (version 3). Patients completed quality-of-life questionnaires at defined intervals.
  
  
  RESULTS
  Groups of 15 patients received 45 Gy, 47.5 Gy, and 50 Gy in five fractions (45 total patients). The median follow-up is 30 months (range, 3 to 36 months), 18 months (range, 0 to 30 months), and 12 months (range, 3 to 18 months) for the 45 Gy, 47.5 Gy, and 50 Gy groups, respectively. For all patients, GI grade ≥ 2 and grade ≥ 3 toxicity occurred in 18% and 2%, respectively, and GU grade ≥ 2 and grade ≥ 3 toxicity occurred in 31% and 4%, respectively. Mean AUA scores increased significantly from baseline in the 47.5-Gy dose level (P = .002) as compared with the other dose levels, where mean values returned to baseline. Rectal quality-of-life scores (Expanded Prostate Cancer Index Composite) fell from baseline up to 12 months but trended back at 18 months. In all patients, PSA control is 100% by the nadir + 2 ng/mL failure definition.
  
  
  CONCLUSIONS
  Dose escalation to 50 Gy has been completed without DLT. A multicenter phase II trial is underway treating patients to 50 Gy in five fractions to further evaluate this experimental therapy.
authors.affiliation: University of Texas Southwestern, Dallas, TX 75390, USA.
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Boike
authors.forename: Yair
authors.initials: Y
authors.lastname: Lotan
authors.forename: L Chinsoo
authors.initials: LC
authors.lastname: Cho
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Brindle
authors.forename: Paul
authors.initials: P
authors.lastname: DeRose
authors.forename: Xian-Jin
authors.initials: XJ
authors.lastname: Xie
authors.forename: Jingsheng
authors.initials: J
authors.lastname: Yan
authors.forename: Ryan
authors.initials: R
authors.lastname: Foster
authors.forename: David
authors.initials: D
authors.lastname: Pistenmaa
authors.forename: Alida
authors.initials: A
authors.lastname: Perkins
authors.forename: Susan
authors.initials: S
authors.lastname: Cooley
authors.forename: Robert
authors.initials: R
authors.lastname: Timmerman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011788:Quality of Life; D016634:Radiosurgery / Q000009:adverse effects* / Q000379:methods; D011879:Radiotherapy Dosage; D012306:Risk