Long-term results of conformal radiotherapy for prostate cancer: impact of dose escalation on biochemical tumor control and distant metastases-free survival outcomes

Int J Radiat Oncol Biol Phys. 2008 Jul 15;71(4):1028-33. doi: 10.1016/j.ijrobp.2007.11.066. Epub 2008 Feb 14.

Abstract

Purpose: To report prostate-specific antigen (PSA) relapse-free survival and distant metastases-free survival (DMFS) outcomes for patients with clinically localized prostate cancer treated with high-dose conformal radiotherapy.

Methods and materials: Between 1988 and 2004, a total of 2,047 patients with clinically localized prostate cancer were treated with three-dimensional conformal radiotherapy or intensity-modulated radiotherapy. Prescribed dose levels ranged from 66-86.4 Gy. Median follow-up was 6.6 years (range, 3-18 years).

Results: Although no differences were noted among low-risk patients for the various dose groups, significant improvements were observed with higher doses for patients with intermediate- and high-risk features. In patients with intermediate-risk features, multivariate analysis showed that radiation dose was an important predictor for improved PSA relapse-free survival (p < 0.0001) and improved DMFS (p = 0.04). In patients with high-risk features, multivariate analysis showed that the following variables predict for improved PSA relapse-free survival: dose (p < 0.0001); age (p = 0.0005), and neoadjuvant-concurrent androgen deprivation therapy (ADT; p = 0.01). In this risk group, only higher radiation dose was an important predictor for improved DMFS (p = 0.04).

Conclusions: High radiation dose levels were associated with improved biochemical tumor control and decreased risk of distant metastases. For high-risk patients, despite the delivery of high radiation dose levels, the use of ADT conferred an additional benefit for improved tumor control outcomes. We observed a benefit for ADT in high-risk patients who received higher doses.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Cohort Studies
  • Disease-Free Survival
  • Dose Fractionation, Radiation
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Neoplasm Recurrence, Local / mortality*
  • Neoplasm Recurrence, Local / prevention & control*
  • New York / epidemiology
  • Prevalence
  • Prognosis
  • Prostatic Neoplasms / mortality*
  • Prostatic Neoplasms / therapy*
  • Radiotherapy / statistics & numerical data*
  • Risk Assessment / methods*
  • Risk Factors
  • Treatment Outcome