Population-based study of biochemical and survival outcomes after permanent 125I brachytherapy for low- and intermediate-risk prostate cancer.

Objectives: To analyze the biochemical and survival outcomes after permanent low-dose-rate prostate brachytherapy in a large, consecutive, population-based cohort of patients.

Methods: A total of 1006 consecutive implants were performed from July 20, 1998 to October 23, 2003 for men with low-risk and "low-tier" intermediate-risk prostate cancer. The prescribed minimal peripheral dose was 144 Gy, using 0.33 mCi (125)I sources and a preplan technique with a strong posterior-peripheral dose bias. Most patients (65%) had received 6 months of androgen deprivation therapy. Supplemental external beam radiotherapy was not used. The prognostic features, dose metrics, and follow-up data were prospectively collected. Kaplan-Meier and Cox regression analyses were used to assess the factors associated with freedom from biochemical recurrence and survival.

Results: The median patient age at treatment was 66 years. The median follow-up was 54 months for biochemical outcomes and 66 months for survival. The actuarial freedom from biochemical recurrence rate was 95.6% +/- 1.6% at 5 years and 94.0% +/- 2.2% at 7 years. On multivariate analysis, the pretreatment prostate-specific antigen level (P = .03) and androgen deprivation therapy use (P = .04) were predictive of the freedom from biochemical recurrence. The actuarial rates of distant metastasis and disease-specific death at 5 years were both <1%. The overall survival rate at 5 years was 95.2% +/- 1.4% and was 93.4% +/- 1.8% at 7 years. On multivariate analysis, only age was predictive of overall survival (P = .011).

Conclusions: When consistently planned and delivered, low-dose-rate brachytherapy, without supplemental external beam radiotherapy or intraoperative planning, can produce cancer-specific outcomes for men with low- and "low-tier" intermediate-risk prostate cancer at least equal to that produced by dose-escalated external beam radiotherapy or surgical prostatectomy.