title: The dose-response of salvage radiotherapy following radical prostatectomy: A systematic review and meta-analysis.
abstract: To date neither the optimal radiotherapy dose nor the existence of a dose-response has been established for salvage RT (SRT).
  
  
  
  A systematic review from 1996 to 2015 and meta-analysis was performed to identify the pathologic, clinical and treatment factors associated with relapse-free survival (RFS) after SRT (uniformly defined as a PSA>0.2ng/mL or rising above post-SRT nadir). A sigmoidal dose-response curve was objectively fitted and a non-parametric statistical test used to determine significance.
  
  
  
  71 studies (10,034 patients) satisfied the meta-analysis criteria. SRT dose (p=0.0001), PSA prior to SRT (p=0.0009), ECE+ (p=0.039) and SV+ (p=0.046) had significant associations with RFS. Statistical analyses confirmed the independence of SRT dose-response. Omission of series with ADT did not alter results. Dose-response is well fit by a sigmoidal curve (p=0.0001) with a TCD50of 65.8Gy, with a dose of 70Gy achieving 58.4% RFS vs. 38.5% for 60Gy. A 2.0% [95% CI 1.1-3.2] improvement in RFS is achieved for each Gy. The SRT dose-response remarkably parallels that for definitive RT of localized disease.
  
  
  
  This study provides level 2a evidence for dose-escalated SRT>70Gy. The presence of an SRT dose-response for microscopic disease supports the hypothesis that prostate cancer is inherently radio-resistant.
authors.affiliation: Department of Radiation Oncology, UCLA School of Medicine, Los Angeles, United States. Electronic address: crking@mednet.ucla.edu.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: King
mesh_terms: D003131:Combined Modality Therapy; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008297:Male; D011468:Prostatectomy / Q000379:methods*; D011471:Prostatic Neoplasms / Q000401:mortality / Q000628:therapy*; D011879:Radiotherapy Dosage; D016879:Salvage Therapy / Q000379:methods
keywords: PSA; Prostate cancer; Prostatectomy; Salvage radiotherapy