title: First-year PSA kinetics and minima after prostate cancer radiotherapy are predictive of overall survival.
abstract: OBJECTIVE
  We analyzed whether first-year prostate-specific antigen (PSA) kinetics and minima are predictive of overall survival (OS).
  
  
  METHODS
  The data set contained 1,174 patients treated with external beam radiotherapy (RT) from 1987 to 2001. The relative rate of change (lambda) in post-RT PSA values during the first year (13.5 months) was computed using regression analysis of ln(PSA) vs. time. We also computed the PSA minimum (mPSA) reached during the same period. Recursive partitioning analysis was used to identify the relevant cutpoints for the factors being investigated for its association with survival: age, pretreatment PSA, radiation dose, relative rate of change in PSA post-RT, and 1-year PSA minimum. For each of the other factors stage, Gleason score and risk group, all possible cutpoints were considered in the multivariate analyses. Significant factors were considered in the multivariate analyses to identify independent predictors for overall survival.
  
  
  RESULTS
  The median value of lambda was -1.0 years(-1) (range, -11.0-5.1 years(-1)). The 1-year minimum had a median of 0.8 ng/mL (range, 0.01-30.9 ng/mL). Recursive partitioning analysis and Cox proportional hazards analyses identified the following pretreatment or treatment factors adversely related to OS: age, Gleason score, stage, and dose. First-year mPSA > or = 4 ng/mL and lambda > 0 were post-RT independent prognostic factors for worse OS.
  
  
  CONCLUSIONS
  First-year post-RT PSA kinetics and minima are early response parameters predictive of overall survival for prostate cancer patients. These factors may be useful in selecting patients for early salvage therapy.
authors.affiliation: Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA. mrcheung@mdanderson.org
authors.forename: Rex
authors.initials: R
authors.lastname: Cheung
authors.forename: Susan L
authors.initials: SL
authors.lastname: Tucker
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Kuban
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood* / Q000401:mortality / Q000532:radiotherapy*; D011829:Radiation Dosage; D050397:Radiotherapy, Intensity-Modulated; D012044:Regression Analysis; D013997:Time Factors
chemical_list: D017430:Prostate-Specific Antigen