The Effect of Brachytherapy, External Beam Irradiation and Hormonal Therapy on Prostate Volume

Purpose

We describe the effects of prostate brachytherapy with or without hormonal therapy, or external beam irradiation on gland volume.

Materials and Methods

A total of 600 men with localized prostate cancer underwent ¹²⁵I (357), ¹⁰³Pd (118) or partial ¹⁰³Pd combined with external beam irradiation (125) brachytherapy. Of the 600 men 299 (49.8%) received 3 to 9 months of hormonal therapy, which was initiated 3 months before implantation. Hormonal therapy consisted of luteinizing hormone-releasing hormone agonist plus antiandrogen in 251, luteinizing hormone-releasing hormone agonist in 41 and flutamide plus finasteride in 7. Prostate volume measurements were made before the initiation of hormonal therapy, at implantation and yearly. Median followup was 5.2 years. Associations were tested by chi-square analysis. Means were compared by 1-way ANOVA and the Student t test.

Results

Median initial prostate volume was 38.5 cc (range 9.2 to 151.5). Pre-implantation hormonal therapy resulted in a median prostate volume decrease of 33.1%. The mean reduction for luteinizing hormone-releasing hormone agonist was 27.6%, for luteinizing hormone-releasing hormone agonist plus antiandrogen it was 32.8% and for flutamide plus finasteride it was 10.8% (p = 0.003). Prostate volume decreased 36.6% by year 1, 42.4% by year 4, 45.6% by year 6 and 51.2% by year 8 (p <0.0001). There was no difference in prostate volume reduction at year 1 between men receiving hormonal therapy vs implantation alone. Patients treated with ¹⁰³Pd had a greater prostate volume reduction at 1 year than those who received ¹²⁵I (p = 0.004). Conversely patients treated with hormonal therapy and ¹²⁵I had a smaller prostate volume reduction than those implanted with ¹²⁵I alone (p = 0.023). After year 1 there were no longer differences between any groups.

Conclusions

Luteinizing hormone-releasing hormone agonist plus antiandrogen is more successful for reducing prostate volume before prostate brachytherapy than luteinizing hormone-releasing hormone agonist or flutamide plus finasteride. Hormonal therapy offered no advantage over implantation alone for post-implantation prostate volume reduction. ¹⁰³Pd appears to reduce prostate volume more rapidly than ¹²⁵I but this advantage is lost by year 2. No rebound in prostate volume was noted at longer followup.

Key Words: prostate, prostatic neoplasms, brachytherapy, antiandrogens

Abbreviations and Acronyms: BPH, benign prostatic hyperplasia, EBRT, external beam irradiation, FF, flutamide and finasteride, HT, hormonal therapy, LA, LHRHa plus antiandrogen, LHRHa, luteinizing hormone-releasing hormone agonist, PV, prostate volume