Interval to biochemical failure highly prognostic for distant metastasis and prostate cancer-specific mortality after radiotherapy

Int J Radiat Oncol Biol Phys. 2008 Jan 1;70(1):59-66. doi: 10.1016/j.ijrobp.2007.05.047. Epub 2007 Oct 4.

Abstract

Purpose: Few biochemical parameters have been related to mortality. The present study examined the clinical utility of the interval to biochemical failure (IBF) as a prognostic factor for distant metastasis (DM) and prostate cancer-specific mortality (PCSM) after radiotherapy.

Methods and materials: The study group consisted of 211 T1c-T3Nx-N0M0 patients who had experienced BF among 1,174 men treated with three-dimensional conformal radiotherapy alone. Biochemical failure was defined as a post-treatment prostate-specific antigen (PSA) level of at, or greater than, the PSA nadir plus 2 ng/mL. Cox proportional hazards modeling was used to identify independent predictors of DM and PCSM on multivariate analysis.

Results: An IBF of <18 months was independently predictive for DM (p = 0.008), as was a Gleason score of 7-10 (p = 0.0005), PSA nadir >or=2 ng/mL (p = 0.04), and decreasing radiation dose (p = 0.02) on multivariate analysis, including increasing pretreatment PSA level, PSA nadir >or=2.5 ng/mL, PSA doubling time of <3 months, and Stage T3 disease. An IBF of <18 months was the only predictor of PCSM (p = 0.0003) in the same model. The actuarial 5-year DM rate for an IBF of <18 vs. >or=18 months was 52% vs. 20% (p < 0.0001), and the actuarial PCSM rate was 36% vs. 6%, respectively (p = 0.0001).

Conclusions: The IBF is an important descriptor of the PSA kinetics after radiotherapy to identify men at high risk of clinical failure and death. A IBF of <18 months could aid in selecting men for early, aggressive salvage therapy or participation in a clinical trial.

Publication types

  • Evaluation Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Analysis of Variance
  • Humans
  • Male
  • Middle Aged
  • Neoplasm Staging
  • Prognosis
  • Proportional Hazards Models
  • Prostatic Neoplasms / blood
  • Prostatic Neoplasms / pathology
  • Prostatic Neoplasms / radiotherapy*
  • Radiotherapy, Conformal*
  • Time Factors
  • Treatment Failure