Headline data from the REduction by DUtasteride of prostate Cancer Events (REDUCE) trial was presented at the American Urological Association in Chicago, Illinois. The study population was men between the ages of 50 and 75 who were at increased risk for prostate cancer with prostate specific antigen (PSA) levels between 2.5 and 10 ng/mL (men aged 50 to 60 years) and between 3.0 and 10.0 ng/mL (men aged greater than 60 years). REDUCE achieved its primary endpoint and demonstrated that dutasteride significantly reduced the risk of all biopsy-detectable prostate cancer by 23 per cent (p<0.0001) over four years. A total of 1516 cancers were seen, with 659 in the dutasteride arm and 857 in the placebo arm.

A key secondary endpoint was Gleason score at the time of diagnosis. The study endpoint showed no statistically significant difference in high grade tumours defined as Gleason scores 7 to 10 (233 out of 3406 patients or 6.8 per cent for placebo, vs. 220 out of 3298 patients or 6.7 per cent for dutasteride, p= 0.81) over the four year study period. In the Gleason scores 8-10, although a difference was seen over the four years, it was not statistically significant (19/3406 (0.6 per cent) for placebo vs. 29/3298 (0.9 per cent) for dutasteride, p=0.15).

The most common side effects reported, related to treatment, were erectile dysfunction (5.7 per cent placebo vs. 9.0 per cent dutasteride), decreased libido (1.6 per cent placebo vs. 3.3 per cent dutasteride), gynecomastia (1.0 per cent placebo vs. 1.9 per cent dutasteride). These adverse events are consistent with what has been previously reported in studies of dutasteride.

Further analysis will be included in the manuscript which will be prepared and submitted for publication in a peer review journal this year.

Dutasteride is not approved or licensed to treat or reduce the risk of prostate cancer.

The REDUCE trial is a international, randomised, double-blind, placebo-controlled, parallel group study of the efficacy and safety of dutasteride, 0.5 mg administered daily for four years to reduce the risk of biopsy-detectable prostate cancer.