The importance of an exponential prostate-specific antigen decline after external beam radiotherapy for intermediate risk prostate cancer

Cancer Epidemiol. 2012 Apr;36(2):e137-41. doi: 10.1016/j.canep.2011.10.007. Epub 2011 Nov 16.

Abstract

Background: To study the influence of an exponential prostate-specific antigen (PSA) decline on biochemical failure after external-beam radiotherapy (EBRT).

Methods: We analyzed 114 patients with intermediate risk prostate cancer (Gleason≤6 and PSA 10-20 or Gleason 7 and PSA <10). Patients were randomized between EBRT doses of either 70.2 Gy or 79.2 Gy (1.8 Gy per day). All patients had a follow up of at least six PSA measurements post-EBRT. Exponential decline and PSA half life were included in a Cox regression analysis for factors associated with biochemical failure.

Results: A total of 80/114 (70.2%) patterns were classified as having an exponential PSA decline. Both exponential decline (HR 0.115, 95%CI 0.03-0.44, p=0.0016) and PSA half life ratio were statistically significant predictors (HR 1.03 (95% CI 1.01-1.06)) of biochemical failure. In the model predicting for exponential decline, none of the factors were significant.

Conclusion: Patients with an exponential PSA decline show a better biochemical outcome in the long term.

Publication types

  • Clinical Trial, Phase III
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Humans
  • Male
  • Neoplasm Grading
  • Neoplasm Recurrence, Local / blood
  • Proportional Hazards Models
  • Prostate-Specific Antigen / blood*
  • Prostatic Neoplasms / blood*
  • Prostatic Neoplasms / radiotherapy*
  • Radiotherapy Dosage

Substances

  • Prostate-Specific Antigen