title: Percentage of cancer volume in biopsy cores is prognostic for prostate cancer death and overall survival in patients treated with dose-escalated external beam radiotherapy.
abstract: OBJECTIVE
  To investigate the prognostic utility of the percentage of cancer volume (PCV) in needle biopsy specimens for prostate cancer patients treated with dose-escalated external beam radiotherapy.
  
  
  METHODS
  The outcomes were analyzed for 599 men treated for localized prostate cancer with external beam radiotherapy to a minimal planning target volume dose of 75 Gy (range, 75-79.2). We assessed the effect of PCV and the pretreatment and treatment-related factors on the freedom from biochemical failure, freedom from metastasis, cause-specific survival, and overall survival.
  
  
  RESULTS
  The median number of biopsy cores was 7 (interquartile range, 6-12), median PCV was 10% (interquartile range, 2.5-25%), and median follow-up was 62 months. The PCV correlated with the National Comprehensive Cancer Network risk group and individual risk features, including T stage, prostate-specific antigen level, Gleason score, and percentage of positive biopsy cores. On log-rank analysis, the PCV stratified by quartile was prognostic for all endpoints, including overall survival. In addition, the PCV was a stronger prognostic factor than the percentage of positive biopsy cores when the two metrics were analyzed together. On multivariate analysis, the PCV predicted a worse outcome for all endpoints, including freedom from biochemical failure, (hazard ratio, 1.9; p = .0035), freedom from metastasis (hazard ratio, 1.7, p = .09), cause-specific survival (hazard ratio, 3.9, p = .014), and overall survival (hazard ratio, 1.8, p = .02).
  
  
  CONCLUSIONS
  For patients treated with dose-escalated external beam radiotherapy, the volume of cancer in the biopsy specimen adds prognostic value for clinically relevant endpoints, particularly in intermediate- and high-risk patients. Although the PCV determination is more arduous than the percentage of positive biopsy cores, it provides superior risk stratification.
authors: Department of Radiation Oncology, University of Michigan Medical Center, Ann Arbor, MI 48109-5010, USA.
authors: Sean M
authors: SM
authors: Vance
authors: Matthew H
authors: MH
authors: Stenmark
authors: Kevin
authors: K
authors: Blas
authors: Schulyer
authors: S
authors: Halverson
authors: Daniel A
authors: DA
authors: Hamstra
authors: Felix Y
authors: FY
authors: Feng
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001707:Biopsy, Needle; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D011379:Prognosis; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D050397:Radiotherapy, Intensity-Modulated; D016896:Treatment Outcome; D047368:Tumor Burden
chemical_list: D017430:Prostate-Specific Antigen