Impact of Hormonal Therapy on Intermediate Risk Prostate Cancer Treated With Combination Brachytherapy and External Beam Irradiation

Purpose

We assessed the impact of androgen suppressive therapy on biochemical failure in patients with intermediate risk prostate cancer treated with brachytherapy and external beam irradiation.

Materials and Methods

From 1994 to 2006, 432 patients with intermediate risk prostate cancer as defined by the National Comprehensive Cancer Network were treated with low dose rate brachytherapy and external beam irradiation with or without 9 months of androgen suppressive therapy. Gleason score was 7 in 76% of cases and prostate specific antigen was 1.4 to 20 ng/ml (median 7.6). Of the patients 350 received androgen suppressive therapy and 82 did not. The biologically effective dose was 142 to 280 Gy2 (median 206). Followup was 23 to 155 months (median 56).

Results

The overall 8-year biochemical failure-free rate using the Phoenix definition in patients with vs without androgen suppressive therapy was 92% vs 92% (p = 0.4). The therapy had no significant impact on the biochemical failure-free rate in patients with Gleason score 7 (92% vs 90.5%, p = 0.55), prostate specific antigen 10 to 20 ng/ml (92% vs 100%, p = 0.32), T2b-T2c disease (89.5% vs 97%, p = 0.27) and more than 1 intermediate risk feature (90% vs 100%, p = 0.2).

Conclusions

We addressed the relative importance of radiation dose vs hormonal therapy for intermediate risk prostate cancer. With high biologically effective dose combination treatment androgen suppressive therapy did not have a significant impact on the 8-year biochemical failure-free rate. We question its routine use in this setting.

Key Words: prostate, prostatic neoplasms, brachytherapy, radiotherapy, androgen antagonists

Abbreviations and Acronyms: AST, androgen suppressive therapy, BED, biologically effective dose, D90, dose delivered to hottest 90% of prostate, EBRT, external beam irradiation, FFBF, freedom from biochemical failure, IMRT, intensity modulated radiation therapy, PSA, prostate specific antigen