Can J Urol
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Randomized Controlled Trial Multicenter Study Comparative Study
Dutasteride and bicalutamide in patients with hormone-refractory prostate cancer: the Therapy Assessed by Rising PSA (TARP) study rationale and design.
Bicalutamide blocks androgen action in men with prostate cancer but has low affinity for the androgen receptor compared to dihydrotestosterone (DHT). Dutasteride, a dual 5-reductase inhibitor (5ARI), blocks the conversion of testosterone to DHT, reduces tumor volume and improves PSA in prostate cancer. Bicalutamide should be a more effective antiandrogen if it competes against intraprostatic testosterone, rather than DHT, for the androgen receptor. The Therapy Assessed by Rising PSA (TARP) study investigates dutasteride in combination with bicalutamide to prevent or delay disease progression in patients with castrate-refractory prostate cancer (CRPC) after initial androgen deprivation therapy. ⋯ TARP will be the first study to evaluate the effects of dutasteride and an antiandrogen in patients failing GnRH analogue and help elucidate the potential role of a dual 5ARI in reducing the rate of progression in non-metastatic CRPC.