Oral drugs to treat erectile dysfunction after radical treatment for prostate cancer (PCa) do not affect the risk of biochemical recurrence (BCR) of disease, regardless of the cumulative number of pills taken, a new study suggests.

Stacy Loeb, MD, of New York University, and colleagues conducted a nested case-control study using the National Prostate Cancer Registry of Sweden linked to the Prescribed Drug Register. The study compared 293 men who experienced BCR after radical prostatectomy (RP) with 5,767 BCR-free controls. After adjusting for marital status, income, education, PSA level, clinical stage, Gleason score, and proportion of positive biopsies, Dr. Loeb’s group found no significant association between phosphodiesterase type 5 inhibitor (PDE5i) use and BCR following either RP or radiation treatment, according to a paper published online ahead of print in European Urology.

Patients with a greater cumulative number of PDE5i pills were not at higher risk of BCR following RP, after adjusting for pathologic tumor features.

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“A change in clinical practice regarding PDE5i use after PCa treatment is not warranted,” the authors concluded.

The new study corroborates recently published findings by Andrea Gallina, MD, and colleagues at IRCCS Ospedale San Raffaele, Milan, Italy, who examined PDE5i use and BCR in 2,579 men who underwent bilateral nerve-sparing RP. The number of PDE5i pills taken was not significantly associated with BCR, after adjusting for clinicopathologic features, the researchers reported in European Urology (2015;68:750-753).

Study strengths included the availability of population-based data from healthcare registries and demographic databases in Sweden, “which are real-world data of high quality,” Dr. Loeb’s team noted. “Comprehensive linkages provide complete and detailed data, including PCa treatment outcomes, exact cumulative PDE5i exposure, and information on putative confounders including socioeconomic factors.”

The researchers also acknowledged study limitations, including assessment of PDE5i use based on records for filled prescriptions and an insufficient sample size to examine the association between cumulative PDE5i pills and BCR after radiotherapy. In addition, data regarding pretreatment PDE5i use were not available for the study population.