Objective: To evaluate the additional effects of mirabegron to alpha-1 adrenergic antagonist on lower urinary tract symptoms of patients who underwent 125I-brachytherapy for prostate cancer.
Patients and methods: Patients who underwent 125I-brachytherapy for prostate cancer (cT1-cT3aN0M0) in a single institute between September 2016 and October 2018 were enrolled in the randomized, non-placebo, open-labeled, paralleled study. Patients were randomly distributed (1:1) to combination group (tamsulosin (0.2 mg/day) plus mirabegron (50 mg/day)) or tamsulosin-alone group after 125I -brachytherapy by envelope method. The primary endpoint was the change from baseline in mean voided volume per micturition 3 months after 125I brachytherapy. The secondary endpoints included the changes from baseline of International Prostate Symptom Score, Overactive Bladder Symptom Score, and Expanded Prostate Cancer Index Composite scores and 24 hours urinary frequency after 3 months after 125I brachytherapy.
Results: The mean changes in volume voided per micturition in the combination (n = 108) and tamsulosin-alone (n = 110) groups were -62.5 (standard deviation, ±53.8) and -68.0 (standard deviation, ±52.7), respectively (P = .17). The change in Overactive Bladder Symptom Score in combination group (P = .02) was more moderate than in tamsulosin-alone group; and 24 hour urinary frequency in combination group was lower (P = .03) than in tamsulosin-alone group. Retention rates within 3 months after 125I-brachytherapy in the mirabegron and tamsulosin-alone groups were 7.3% (9/122) and 6.0% (7/118), respectively (P = .80).
Conclusion: Tamsulosin and mirabegron combination therapy after 125I-brachytherapy did not improve voided volume per micturition compared to tamsulosin-only treatment. However, it could improve frequent urination and overactive bladder symptoms.
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