title: In patients experiencing biochemical failure after radiotherapy, pretreatment risk group and PSA velocity predict differences in overall survival and biochemical failure-free interval.
abstract: OBJECTIVE
  To characterize the demographics and survival outcomes of localized prostate cancer patients who developed biochemical failure (BF) according to a prostate-specific antigen (PSA) nadir plus 2 ng/mL.
  
  
  METHODS
  We identified 375 prostate cancer patients who had undergone external beam radiotherapy without androgen deprivation therapy but with sufficient PSA data to study PSA kinetics. Of these patients, we identified 82 with BF. The pretreatment PSA velocity was calculated for each patient.
  
  
  RESULTS
  For the BF cohort, 26% were low-risk and 74% were intermediate- or high-risk patients. Of the 82 BF patients, 16 (20%) were noted to have both low-risk disease and a pretreatment low PSA velocity of < or =2 ng/mL/y (termed "low-risk low-velocity" [LRLV]). The remaining BF patients had either intermediate- or high-risk features or a high PSA velocity >2 ng/mL/y (termed "higher risk" [HR]). For patients who had BF, the LRLV group had a delayed median time to BF of 55 months compared with 33 months for the HR patients (p = 0.04). With a median clinical follow-up of 112 months, the 5-year overall survival rate was 100% for the LRLV BF patients vs. 84% for the HR patients (p = 0.02).
  
  
  CONCLUSIONS
  We observed that LRLV BF patients represent a sizeable proportion of all patients with treatment failure. However, when comparing LRLV BF with HR BF patients, the former had significantly better overall survival and a longer interval to BF. This suggests that not all BF events are equivalent and emphasizes the challenges associated with using BF alone as a surrogate for a survival endpoint.
authors.affiliation: Department of Radiation Oncology, University of Michigan, 1500 E. Medical Center Drive, Ann Arbor, MI 48109, USA. dsoto@med.umich.edu
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Soto
authors.forename: Rebecca R
authors.initials: RR
authors.lastname: Andridge
authors.forename: Charlie C
authors.initials: CC
authors.lastname: Pan
authors.forename: Scott G
authors.initials: SG
authors.lastname: Williams
authors.forename: Jeremy M G
authors.initials: JM
authors.lastname: Taylor
authors.forename: Howard M
authors.initials: HM
authors.lastname: Sandler
mesh_terms: D000368:Aged; D018572:Disease-Free Survival; D006801:Humans; D008297:Male; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D020266:Radiotherapy, Conformal; D012189:Retrospective Studies; D012306:Risk; D013997:Time Factors
chemical_list: D017430:Prostate-Specific Antigen