Researchers performed a randomized, placebo-controlled Phase II trial of men with localized prostate cancer and a rising prostate-specific antigen (PSA) level post-primary treatment. The men were randomized to receive Avodart (dutasteride @ 0.5 mg/day) or to receive a placebo.

All of the men were receiving intermittent androgen deprivation therapy (IADT), which was stopped at month 9 if the PSA level was greater than 1.0 ng/mL. ADT was resumed when PSA increased to greater than or equal to 5.0 ng/mL. The trial end points included calculating the time the men were off treatment, their PSA nadir after 9 months of IADT, serum testosterone and dihydrotestosterone levels, and time to castrate-resistant prostate cancer (rising PSA while testosterone levels remain greater than 50 ng/mL).
The researchers found they had 80 evaluable men who completed one treatment cycle : 49 receiving dutasteride and 38 receiving a placebo.

The median time off treatment for men reaching greater than or equal to 5 ng/mL was 18.6 and 16.7 months for dutasteride and placebo, respectively (p = 0.7600). The median PSA nadir at 9 months was 0.1 and 0.075 ng/mL, respectively (p = 0.4486). There were no cases where a man developed castrate resistant prostate cancer.

This small-scale Phase II randomized controlled trial showed no benefit to the addition of Avodart (dutasteride) to an IADT regimen. However, the trial was too short having the subject men go through only one cycle of IADT. It would have been very helpful if the researchers had extended this trial through a number of additional cycles.

Can Urol Assoc J. 2014 Nov;8(11-12):E789-94.
doi: 10.5489/cuaj.2332

PubMed Abstract
PMID: 25485005

Joel T. Nowak, M.A., M.S.W.