67th Annual Meeting Abstracts

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The Effect of the Combination of Dutasteride and Tamsulosin on the Transition Zone of the Prostate
*Paul Gagnier, *Timothy H Wilson
Research Triangle Park, Durham, NC

Introduction: Dutasteride decreases total prostate volume (PV) and transition zone volume (TZV) in BPH. However, the combination of dutasteride with an alpha-blocker and its effect on these two areas is unknown. We determined the effects of combination therapy on PV, TZV and the transition zone index (TZI).
Materials and Methods: A total of 4,844 men ≥50 years with BPH, AUA symptom score of ≥12, PV ≥30 cc, PSA ≥1.5 ng/ml, and ≤10 ng/ml, and peak urinary flow rate ≤15 ml/second were randomized to dutasteride 0.5 mg, tamsulosin 0.4 mg or the combination of the two daily for 2 years. Prostate TZV was measured in a 10% subset of the subjects with transrectal ultrasound at baseline and after 1 and 2-years. PV, TZV and the TZI (TZV/PV ratio) were calculated. Patients were stratified into tertiles according to baseline PV. Treatment comparisons within PV tertiles were performed using a Wilcoxon rank-sum test.
Results: Within each PV tertile, combination therapy and dutasteride monotherapy significantly (p<0.001) decreased PV and TZV compared with tamsulosin monotherapy. However, there was no significant difference between combination therapy and dutasteride monotherapy.
Conclusions: Dutasteride and combination therapy significantly decreased total PV and TZV compared with tamsulosin monotherapy regardless of baseline PV value.

Percent Change From Baseline in Total Prostate Volume and Transition Zone Volume (LOCF) at Month 24

Median [n]	Dut 0.5 + Tam 0.4 mg N = 153	Dut 0.5 mg N = 164	Tam 0.4 mg N = 160
PV
Baseline PV <44cc	-25.1 [54]	-28.8 [50]	-7.0 [54]
Baseline 44cc to <63cc	-24.0 [51]	-25.9 [53]	5.6 [53]
Baseline PV > 63cc	-20.3 [48]	-29.8 [61]	3.0 [53]
TZV
Baseline PV <44cc	-24.1 [54]	-29.7 [50]	-0.5 [54]
Baseline 44cc to <63cc	-24.0 [51]	-26.6 [53]	11.6 [53]
Baseline PV > 63cc	-24.0 [48]	-31.2 [61]	2.8 [53]

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