Effect of dutasteride on LAPC4 tumor regrowth 14 days after pellet implantation (day 28). A. Effect of dutasteride on LAPC4 tumor volume. Tumor volume in intact (I), intact + dutasteride (I+D), castrated with testosterone replacement (C+T), castrated + testosterone replacement + dutasteride (C+T+D) was determined at day 28 post-castration. Values are presented as mean ± SEM. Number of animals in each group is represented in parentheses. B. Response of androgen-sensitive xenograft tumors LAPC4, LuCaP35 and LNCaP to 5α-reductase inhibition during testosterone stimulated regrowth after 4 days of treatment (day 18). Tumor volume in castrated animals treated with testosterone (C+T) and testosterone plus dutasteride (C+T+D) for 4 days or finasteride (C+T+F) for 4 days. C. Response of androgen-sensitive xenograft tumors LAPC4, LuCaP35 and LNCaP to 5α-reductase inhibition during testosterone stimulated regrowth after 14 days of treatment (day 28). Tumor volume in castrated animals treated with testosterone (C+T) and testosterone plus dutasteride (C+T+D) for 14 days or finasteride (C+T+F) for 10 days. Data from LuCaP35 and LNCaP derived from previously published data [18,22]. Number of animals in each group is represented in parentheses. (*, P < 0.05).