title: Stereotactic body radiation therapy (SBRT) for clinically localized prostate cancer: the Georgetown University experience.
abstract: BACKGROUND
  Stereotactic body radiation therapy (SBRT) delivers fewer high-dose fractions of radiation which may be radiobiologically favorable to conventional low-dose fractions commonly used for prostate cancer radiotherapy. We report our early experience using SBRT for localized prostate cancer.
  
  
  METHODS
  Patients treated with SBRT from June 2008 to May 2010 at Georgetown University Hospital for localized prostate carcinoma, with or without the use of androgen deprivation therapy (ADT), were included in this retrospective review of data that was prospectively collected in an institutional database. Treatment was delivered using the CyberKnife® with doses of 35 Gy or 36.25 Gy in 5 fractions. Biochemical control was assessed using the Phoenix definition. Toxicities were recorded and scored using the CTCAE v.3. Quality of life was assessed before and after treatment using the Short Form-12 Health Survey (SF-12), the American Urological Association Symptom Score (AUA) and Sexual Health Inventory for Men (SHIM) questionnaires. Late urinary symptom flare was defined as an AUA score ≥ 15 with an increase of  ≥ 5 points above baseline six months after the completion of SBRT.
  
  
  RESULTS
  One hundred patients (37 low-, 55 intermediate- and 8 high-risk according to the D'Amico classification) at a median age of 69 years (range, 48-90 years) received SBRT, with 11 patients receiving ADT. The median pre-treatment prostate-specific antigen (PSA) was 6.2 ng/ml (range, 1.9-31.6 ng/ml) and the median follow-up was 2.3 years (range, 1.4-3.5 years). At 2 years, median PSA decreased to 0.49 ng/ml (range, 0.1-1.9 ng/ml). Benign PSA bounce occurred in 31% of patients. There was one biochemical failure in a high-risk patient, yielding a two-year actuarial biochemical relapse free survival of 99%. The 2-year actuarial incidence rates of GI and GU toxicity ≥ grade 2 were 1% and 31%, respectively. A median baseline AUA symptom score of 8 significantly increased to 11 at 1 month (p=0.001), however returned to baseline at 3 months (p=0.60). Twenty one percent of patients experienced a late transient urinary symptom flare in the first two years following treatment. Of patients who were sexually potent prior to treatment, 79% maintained potency at 2 years post-treatment.
  
  
  CONCLUSIONS
  SBRT for clinically localized prostate cancer was well tolerated, with an early biochemical response similar to other radiation therapy treatments. Benign PSA bounces were common. Late GI and GU toxicity rates were comparable to conventionally fractionated radiation therapy and brachytherapy. Late urinary symptom flares were observed but the majority resolved with conservative management. A high percentage of men who were potent prior to treatment remained potent two years following treatment.
authors.affiliation: Department of Radiation Medicine, Georgetown University Hospital, Washington, DC 20007, USA.
authors.forename: Leonard N
authors.initials: LN
authors.lastname: Chen
authors.forename: Simeng
authors.initials: S
authors.lastname: Suy
authors.forename: Sunghae
authors.initials: S
authors.lastname: Uhm
authors.forename: Eric K
authors.initials: EK
authors.lastname: Oermann
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Ju
authors.forename: Viola
authors.initials: V
authors.lastname: Chen
authors.forename: Heather N
authors.initials: HN
authors.lastname: Hanscom
authors.forename: Sarah
authors.initials: S
authors.lastname: Laing
authors.forename: Joy S
authors.initials: JS
authors.lastname: Kim
authors.forename: Siyuan
authors.initials: S
authors.lastname: Lei
authors.forename: Gerald P
authors.initials: GP
authors.lastname: Batipps
authors.forename: Keith
authors.initials: K
authors.lastname: Kowalczyk
authors.forename: Gaurav
authors.initials: G
authors.lastname: Bandi
authors.forename: John
authors.initials: J
authors.lastname: Pahira
authors.forename: Kevin G
authors.initials: KG
authors.lastname: McGeagh
authors.forename: Brian T
authors.initials: BT
authors.lastname: Collins
authors.forename: Pranay
authors.initials: P
authors.lastname: Krishnan
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Dawson
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Taylor
authors.forename: Anatoly
authors.initials: A
authors.lastname: Dritschilo
authors.forename: John H
authors.initials: JH
authors.lastname: Lynch
authors.forename: Sean P
authors.initials: SP
authors.lastname: Collins
mesh_terms: D000230:Adenocarcinoma / Q000097:blood / Q000401:mortality / Q000601:surgery*; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000401:mortality / Q000601:surgery*; D016634:Radiosurgery; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D012189:Retrospective Studies; D016896:Treatment Outcome
chemical_list: D017430:Prostate-Specific Antigen