Dutasteride (Avodart) treatment significantly reduces the relative risk of a prostate cancer (PCa) diagnosis in men with benign prostatic hyperplasia (BPH) undergoing screening with PSA tests and digital rectal examinations (DREs), new findings suggest.

An analysis of data from the Combination of Avodart and Tamsulosin (CombAT) study showed that, compared with tamsulosin therapy alone, dutasteride, either alone or in combination with tamsulosin, was associated with a 40% relative risk reduction of a PCa diagnosis and a 40% reduction in the likelihood of a prostate biopsy, investigators Claus G. Roehrborn, MD, of the University of Texas Southwestern Medical Center in Dallas, and colleagues reported online in European Urology. The relative risk reduction of a PCa diagnosis, versus tamsulosin monotherapy, was 43% in patients who took both dutasteride and tamsulosin and 37% in patients who took dutasteride alone.

CombAT was a four-year double-blind study involving 4,844 men aged 50 years and older with clinically diagnosed moderate to severe BPH, an International Prostate Symptom Score of 12 or higher, prostate volume of 30 mL or more, and serum PSA level of 1.5 to 10 ng/mL. Men underwent annual PSA measurements and DREs, with prostate biopsies performed for cause, such as rising PSA or suspicious DRE findings or nodular areas detected by transrectal ultrasonograph. Subjects were randomly assigned to receive tamsulosin 0.4 mg/day, dutasteride 0.5 mg/day, or a combination of both.

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Over the four-year study period, 539 for-cause prostate biopsies were performed in 472 patients. The majority of for-cause biopsies (73.2%) were performed because of rising PSA. Significantly more men in the tamsulosin arm underwent biopsies than in the dutasteride or combination therapy groups (13.3% vs. 8.8% and 7.1%, respectively).

In addition, PCa was detected in 37 (2.3%) of 1,610 men in the combination arm, 42 (2.6%) of the 1,623 subjects in the dutasteride arm, and 63 (3.9%) of 1,611 men in the tamsulosin group. Among subjects who underwent for-cause biopsies, 295 were positive for PCa in the combination group, 28% in the dutasteride arm, and 24% of the tamsulosin group. Baseline PSA levels were significantly higher in men diagnosed with PCa compared with those not diagnosed with the malignancy (5.1 vs. 3.9 ng/mL), with no differences among the treatment arms.

“Beyond the reduction in PCa detection, the improvement in PSA performance with dutasteride treatment may also result in a lower rate of unnecessary biopsies, a higher biopsy diagnostic yield, and easier identification of cancers likely to be relevant to the practicing clinician,”the investigators observed.