Prostate cancer progression slowed by adding 5-alpha-reductase inhibitor to active surveillance

Orlando, FL-The 5-alpha-reductase inhibitor dutasteride (Avodart), when added to an active surveillance strategy, slows progression of prostate cancer in men with localized disease and decreases patient anxiety, according to findings from a recent phase III trial.

"Men with newly diagnosed prostate cancer treated with dutasteride had the chance of progression reduced by about 40% compared with active surveillance plus placebo," explained lead author Neil Fleshner, MD, head of urology at the University Health Network in Toronto. "More subjects in the dutasteride group had no cancer in the final biopsy [at the end of the 3-year study].

"I'm hoping that these results showing that men may be able to take a drug that slows the growth of prostate cancer will allow more men to pursue active surveillance for even longer periods," added Dr. Fleshner, who presented the results at the Genitourinary Cancers Symposium in Orlando, FL.

Dr. Fleshner said that taking dutasteride reduced anxiety among study participants and would likely do so in the general population. He pointed out that dutasteride, which is currently indicated for treatment of BPH, typically reduces prostate gland size and leads to a reduction in PSA level, which men find reassuring. Conversely, if prostate gland volume is not reduced by dutasteride and there is no accompanying reduction in PSA level, active treatment should be considered.

For the phase III, randomized, placebo-controlled REDEEM (Reduction by Dutasteride of Clinical Progression Events in Expectant Management of Prostate Cancer) study, the researchers randomized 302 men with early-stage localized prostate cancer to treatment with dutasteride or placebo for 3 years.

Prostate biopsies were obtained at 18 months and 3 years; biopsies were also obtained if there were signs of disease progression in patients.

Time to progression (primary endpoint) was superior in the dutasteride group: 54 men (38%) in the dutasteride group had evidence of progression versus 71 men (49%) in the placebo group. This represents a highly significant 38.9% relative risk reduction for disease progression associated with dutasteride treatment (p=.007).

"This is a very important paper, because men with newly diagnosed prostate cancer experience increased anxiety on watchful waiting," said Nicholas Vogelzang, MD, chair and medical director of the Developmental Therapeutics Committee of U.S. Oncology, Las Vegas, who was not involved with the study. "With dutasteride, the drop in PSA level and reduction in the size of the prostate gland reduces any symptoms that may have been present. We have learned that dutasteride also appears to reduce the amount of cancer in the prostate gland. This is an important step forward."

Dutasteride is commonly used to treat BPH and is FDA-approved for that indication. In December 2010, an FDA committee voted against a favorable risk/benefit profile for the drug in reducing the risk of prostate cancer, despite what many have called strong favorable evidence. The drug's maker, GlaxoSmithKline, recently announced that it will no longer pursue approval for the prostate cancer risk reduction indication.

Dr. Fleshner has a financial or other relationship with GlaxoSmithKline.