Background: Intermittent androgen ablation (IAA) was developed with the intention of delaying progression of prostate cancer to androgen-independence and improving quality of life. Our previous studies suggest that relative to dihydrotestosterone (DHT), testosterone (T) is a weak inducer of proliferation and a more potent inducer of differentiation. We hypothesize that administration of finasteride (F), a type-II 5-alpha-reductase inhibitor that increases T and decreases DHT, during the IAA "off-cycle" would enhance the efficacy.
Methods: After LNCaP tumor establishment, nude mice were castrated and randomized to continuous androgen ablation (CAA), continuous androgen ablation plus finasteride (CAA + F), intermittent androgen ablation (IAA), or intermittent androgen ablation plus finasteride (IAA + F).
Results: After one cycle of therapy, mice treated with IAA + F had significantly less tumor growth than the other treatment groups (P = 0.002). Mice treated with IAA + F had the best survival (P = 0.048) and were 3-5 times more likely to be alive 70 days following treatment initiation.
Conclusions: IAA with finasteride provides the most favorable tumor growth kinetics and survival compared to both CAA and standard IAA.
(c) 2005 Wiley-Liss, Inc.