Permanent interstitial brachytherapy in younger patients with clinically organ-confined prostate cancer.

OBJECTIVES: To evaluate biochemical progression-free survival in hormone-naive men 62 years of age or younger with clinically organ-confined prostate cancer who underwent brachytherapy with or without supplemental external beam radiotherapy. METHODS: From April 1995 through December 2000, 119 hormone-naive patients 62 years of age or younger underwent permanent interstitial brachytherapy for clinical T1b-T2cNxM0 (2002 American Joint Committee on Cancer) prostate cancer. No patient underwent seminal vesicle biopsy or pathologic lymph node staging. The median follow-up was 5.4 years. Biochemical progression-free survival was defined by either a prostate-specific antigen (PSA) level of 0.4 ng/mL or less after a nadir or by the American Society for Therapeutic Radiology and Oncology consensus definition. No patient was lost to follow-up. The clinical, treatment, and dosimetric parameters evaluated for biochemical progression-free survival included age, clinical T stage, Gleason score, pretreatment PSA level, risk group, percentage of positive biopsies, isotope, supplemental external beam radiotherapy, prostate volume, brachytherapy planning volume, percentage of the target volume receiving 100%, 150%, and 200% of the prescribed dose, minimal percentage of the prescribed dose covering 90% of the target volume, and tobacco status. RESULTS: For the entire group, the actuarial 7-year biochemical progression-free survival rate was 96.1% and 98.3% for a PSA cutpoint of 0.4 ng/mL or less and for the American Society for Therapeutic Radiology and Oncology consensus definition, respectively. Using a PSA biochemical control definition of 0.4 ng/mL or less, 93.1%, 100%, and 95.2% of the low-risk, intermediate-risk, and high-risk hormone-naive patients were free of biochemical progression. The median post-treatment PSA level for the biochemically disease-free group was less than 0.1 ng/mL. In multivariate analysis, only the pretreatment PSA level predicted the biochemical outcome. CONCLUSIONS: Hormone-naive patients 62 years of age or younger have a high probability of 7-year biochemical progression-free survival after permanent interstitial brachytherapy with or without supplemental external beam radiotherapy.