title: Hypofractionated stereotactic body radiotherapy in low-risk prostate adenocarcinoma: preliminary results of a multi-institutional phase 1 feasibility trial.
abstract: BACKGROUND
  Recent reports using extreme hypofractionated regimens in the treatment of low-risk prostate adenocarcinoma have been encouraging. Here, the authors report on their own multi-institutional experience with extreme hypofractionated stereotactic radiotherapy for early stage disease.
  
  
  METHODS
  In total, at 4 centers, 45 patients with National Comprehensive Cancer Network-defined, low-risk prostate adenocarcinoma were enrolled in a phase 1, multi-institutional trial of hypofractionated radiosurgery with a proprietary radiosurgical device (CyberKnife). Thirty-four patients received 7.5 grays (Gy) delivered in 5 fractions, 9 patients received 7.25 Gy delivered in 5 fractions, and 2 patients received other regimens. The variables evaluated were biochemical progression-free survival (bPFS), prostate-specific antigen (PSA) bounce, and toxicities. Health-related quality of life was evaluated using the Sexual Health Inventory for Men (SHIM), American Urological Association (AUA), and Expanded Prostate Cancer Index Composite (EPIC) questionnaires.
  
  
  RESULTS
  The median follow-up for surviving patients was 44.5 months (range, 0-62 months). The bPFS rate at 3 years was 97.7%. The median PSA declined from 4.9 ng/mL at diagnosis to 0.2 ng/mL at last follow-up, and the median percentage PSA decline at 12 months was 80%. Nine patients experienced at least 1 PSA bounce ≥0.4 ng/mL, and 4 patients experienced 2 PSA bounces. The median time to first PSA bounce was 11.6 months (range, 7.2-18.2 months), and the mean percentage PSA bounce was 1.07 ng/mL. There was 1 episode of late grade 3 urinary obstruction, and there were 2 episodes of late grade 3 proctitis. There was a significant late decline in SHIM and EPIC sexual scores and a small, late decline in the EPIC Bowel domain score.
  
  
  CONCLUSIONS
  In a select population, extreme hypofractionation with stereotactic radiosurgery was safe and effective for the treatment of low-risk prostate adenocarcinoma.
authors.affiliation: Harvard Radiation Oncology Program, Harvard University, 100 Blossom Street, 3, Boston, MA 02114, USA. smmcbride@partners.org
authors.forename: Sean M
authors.initials: SM
authors.lastname: McBride
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Wong
authors.forename: John J
authors.initials: JJ
authors.lastname: Dombrowski
authors.forename: Bonnie
authors.initials: B
authors.lastname: Harkins
authors.forename: Patricia
authors.initials: P
authors.lastname: Tapella
authors.forename: Heather N
authors.initials: HN
authors.lastname: Hanscom
authors.forename: Sean P
authors.initials: SP
authors.lastname: Collins
authors.forename: Irving D
authors.initials: ID
authors.lastname: Kaplan
mesh_terms: D000230:Adenocarcinoma / Q000532:radiotherapy*; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008297:Male; D008875:Middle Aged; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*
chemical_list: D017430:Prostate-Specific Antigen