BERLIN—Regardless of clinical parameters affecting prostate cancer risk (PCa), men who took the dual 5α-reductase inhibitor dutasteride for two to four years reduced their incidence of biopsy-detectable prostate tumors.

The risk was reduced by 16% to 32% across multiple subsets (see table below), according to a subgroup analysis of the REDUCE (Reduction by DUtasteride of prostate Cancer Events) trial presented at joint congress of the European Cancer Organization and European Society for Medical Oncology.

These results confirm the efficacy of dual 5α-reductase inhibition in reducing PCa risk, said Michael Marberger, MD of the University of Vienna in Austria, who presented the results.

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“Regardless of the baseline variable we evaluated, we saw a significant reduction in risk of prostate cancer with dutasteride versus placebo,” Dr. Marberger said. These variables included age, family history, International Prostate Symptom Score (IPSS), number of cores in the baseline biopsy, prostate volume, PSA, percent-free PSA, and BMI.

Findings of the subgroup analysis are consistent with the overall 23% relative risk reduction found for dutasteride in the group as a whole, Dr. Marberger said.

REDUCE included 8,121 men with PSA levels of 2.5 to 10.0 ng/mL (age group 50-60 years) or 3.0 to 10.0 ng/mL (men older than 60). Subjects also were required to have a negative prostate biopsy within six months prior to study entry.

Subjects underwent 10-core biopsies after two and four years of treatment; for-cause biopsies could be performed at any time. The current analysis, which was sponsored by dutasteride maker GlaxoSmithKline, examined risk reduction according to baseline characteristics (see figure).

“In all pre-specified baseline subgroups, risk reduction was observed,” he emphasized.

Dr. Marberger advocated the off-label use of dutasteride for cancer prevention in certain populations, such as men at higher risk due to elevated PSA and large prostate volume. The typical candidate, he added, might be “very motivated” to prevent cancer and willing to accept the potential for side effects, including decreased sexual function and reduced ejaculate volume.


Dutasteride treatment was associated with reductions in the risk of prostate cancer by: 

  • 22.1% in men aged 65 years and older
  • 25.9% in men with baseline IPSS of 8 or higher
  • 16.3% in men with baseline prostate volume of at least 36.6 mL but less than 51.8 mL and by 32.1% in men with a prostate volume of 51.8 mL or greater
  • 23.4% in men with baseline a PSA level of at least 4.9 and less than 6.8 ng/mL and by 23.1% in men with a baseline PSA level of 6.8 ng/mL or greater
  • 25.4% in men with baseline percent-free PSA of 18.6 ng/mL or greater
  • 24.1% in men with baseline BMI of at least 25.5 kg/m2 but less than 28.4 kg/m2