title: Repeated stereotactic body radiotherapy for oligometastatic prostate cancer recurrence.
abstract: OBJECTIVE
  To assess the outcome of prostate cancer (PCa) patients diagnosed with oligometastatic disease at recurrence and treated with stereotactic body radiotherapy (SBRT).
  
  
  METHODS
  Non-castrate patients with up to 3 synchronous metastases (bone and/or lymph nodes) diagnosed on positron emission tomography - computed tomography, following biochemical recurrence after local curative treatment, were treated with (repeated) SBRT to a dose of 50 Gy in 10 fractions or 30 Gy in 3 fractions. Androgen deprivation therapy-free survival (ADT-FS) defined as the time interval between the first day of SBRT and the initiation of ADT was the primary endpoint. ADT was initiated if more than 3 metastases were detected during follow-up even when patients were still asymptomatic. Secondary endpoints were local control, progression free survival (PFS) and toxicity. Toxicity was scored using the Common Terminology Criteria for Adverse Events.
  
  
  RESULTS
  With a median follow-up from time of SBRT of 2 years, we treated 50 patients with 70 metastatic lesions with a local control rate of 100%. The primary involved metastatic sites were lymph nodes (54%), bone (44%), and viscera (2%). The median PFS was 19 mo (95% CI: 13-25 mo) with 75% of recurring patients having ≤3 metastases. A 2nd and 3rd course of SBRT was delivered in 19 and 6 patients respectively. This results in a median ADT-FS of 25 months (20-30 mo). On univariate analysis, only a short PSA doubling time was a significant predictor for both PFS (HR: 0.90, 95% CI: 0.82 - 0.99) and ADT-FS (HR: 0.83; 95% CI: 0.71 - 0.97). Ten patients (20%) developed toxicity following treatment, which was classified as grade I in 7 and grade II in 3 patients.
  
  
  CONCLUSIONS
  Repeated SBRT for oligometastatic prostate cancer postpones palliative androgen deprivation therapy with 2 years without grade III toxicity.
authors.forename: Karel
authors.initials: K
authors.lastname: Decaestecker
authors.forename: Gert
authors.initials: G
authors.lastname: De Meerleer
authors.forename: Bieke
authors.initials: B
authors.lastname: Lambert
authors.forename: Louke
authors.initials: L
authors.lastname: Delrue
authors.forename: Valérie
authors.initials: V
authors.lastname: Fonteyne
authors.forename: Tom
authors.initials: T
authors.lastname: Claeys
authors.forename: Filip
authors.initials: F
authors.lastname: De Vos
authors.forename: Wouter
authors.initials: W
authors.lastname: Huysse
authors.forename: Arne
authors.initials: A
authors.lastname: Hautekiet
authors.forename: Gaethan
authors.initials: G
authors.lastname: Maes
authors.affiliation: Department of Radiotherapy, Ghent University Hospital, De Pintelaan 185, Ghent, Belgium. Piet.ost@ugent.be.
authors.forename: Piet
authors.initials: P
authors.lastname: Ost
mesh_terms: D001859:Bone Neoplasms / Q000401:mortality / Q000556:secondary* / Q000601:surgery*; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality / Q000473:pathology / Q000601:surgery*; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011379:Prognosis; D011446:Prospective Studies; D011471:Prostatic Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D016634:Radiosurgery; D011879:Radiotherapy Dosage; D012086:Reoperation; D015996:Survival Rate; D014057:Tomography, X-Ray Computed