title: High-dose-rate stereotactic body radiation therapy for postradiation therapy locally recurrent prostatic carcinoma: Preliminary prostate-specific antigen response, disease-free survival, and toxicity assessment.
abstract: OBJECTIVE
  Patients with locally recurrent adenocarcinoma of the prostate following radiation therapy (RT) present a challenging problem. We prospectively evaluated the use of "high-dose-rate-like" prostate stereotactic body RT (SBRT) salvage for this circumstance, evaluating prostate-specific antigen response, disease-free survival, and toxicity.
  
  
  METHODS
  Between February 2009 and March 2014, 29 patients with biopsy-proven recurrent locally prostate cancer >2 years post-RT were treated. Median prior RT dose was 73.8 Gy and median interval to SBRT salvage was 88 months. Median recurrence Gleason score was 7 (79% was ≥7). Pre-existing RT toxicity >grade 1 was a reason for exclusion. Magnetic resonance imaging-defined prostate volume including any suspected extraprostatic extension, comprising the planning target volume. A total of 34 Gy/5 fractions was given, delivering a heterogeneous, high-dose-rate-like dose-escalation pattern. Toxicities were assessed using Common Terminology Criteria for Adverse Events, version 3.0, criteria.
  
  
  RESULTS
  Twenty-nine treated patients had a median 24-month follow-up (range, 3-60 months). A median pre-SBRT salvage baseline prostate-specific antigen level of 3.1 ng/mL decreased to 0.65 ng/mL and 0.16 ng/mL at 1 and 2 years, respectively. Actuarial 2-year biochemical disease-free survival measured 82%, with no local failures. Toxicity >grade 1 was limited to the genitourinary domain, with 18% grade 2 or higher and 7% grade 3 or higher. No gastrointestinal toxicity >grade 1 occurred.
  
  
  CONCLUSIONS
  Two-year disease-free survival is encouraging, and the prostate-specific antigen response kinetic appears comparable with that seen in de novo patients treated with SBRT, albeit still a preliminary finding. Grade ≥2 genitourinary toxicity was occasionally seen with no obvious predictive factor. Noting that our only brachytherapy case was 1 of the 2 cases with ≥grade 3 genitourinary toxicity, caution is recommended treating these patients. SBRT salvage of post-RT local recurrence appears clinically feasible, with longer term evaluation required to assess ultimate efficacy and late toxicity rates.
authors.affiliation: Department of Radiation Oncology, Genesis Healthcare Partners, Inc., San Diego, California. Electronic address: dfuller@genhp.com.
authors.forename: Donald B
authors.initials: DB
authors.lastname: Fuller
authors.affiliation: Department of Radiation Oncology, Atlanticare, Egg Harbor, New Jersey.
authors.forename: James
authors.initials: J
authors.lastname: Wurzer
authors.affiliation: Department of Radiation Oncology, Genesis Healthcare Partners, Inc., San Diego, California.
authors.forename: Reza
authors.initials: R
authors.lastname: Shirazi
authors.affiliation: Department of Urology, Genesis Healthcare Partners, Inc., San Diego, California.
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Bridge
authors.affiliation: Department of Radiation Oncology, Atlanticare, Egg Harbor, New Jersey.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Law
authors.affiliation: Department of Radiation Oncology, Genesis Healthcare Partners, Inc., San Diego, California.
authors.forename: George
authors.initials: G
authors.lastname: Mardirossian
mesh_terms: D000230:Adenocarcinoma / Q000097:blood / Q000401:mortality / Q000532:radiotherapy / Q000601:surgery*; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000097:blood / Q000401:mortality / Q000532:radiotherapy / Q000601:surgery*; D058958:Organs at Risk; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000401:mortality / Q000532:radiotherapy / Q000601:surgery*; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated; D015996:Survival Rate; D047368:Tumor Burden
chemical_list: D017430:Prostate-Specific Antigen