Prostate Cancer Radiotherapy Tadalafil Prophylaxis Use ‘Unsupported’

Phosophodiesterase-5 inhibitor treatment fails to reduce the risk of erectile dysfunction associated with prostate cancer radiotherapy

medwireNews: Tadalafil does not protect erectile function during radiotherapy for localised prostate cancer, US researchers say.

The team, led by Thomas Pisansky, from the Mayo Clinic in Rochester, Minnesota, found no significant difference in sexual function or satisfaction in 112 patients randomly assigned to receive the phosphodiesterase-5 inhibitor 5 mg/day over 24 weeks and 109 men given placebo.

The majority (63%) of men received external beam radiotherapy, while the remainder underwent brachytherapy.

Overall, 79% of tadalafil-treated patients achieved off-drug spontaneous erection at weeks 28 to 30, as did 74% of placebo-treated controls. Nor was there a significant difference in the rate of erectile function in the tadalafil and placebo groups after 1 year of follow-up, at 72% versus 71%.

“These findings do not support the scheduled once-daily use of tadalafil to prevent ED [erectile dysfunction] in men undergoing radiotherapy for localized prostate cancer,” the researchers report in JAMA.

They also found that the patient groups did not differ with regard to erectile function markers, such as orgasmic function, sexual desire and intercourse satisfaction, or by the sexual adjustment domains of desire, dysfunction, activity, satisfaction and fatigue.

And Sexual Adjustment Questionnaire scores for the partners of 42 tadalafil-treated patients and 40-placebo-treated patients were comparable both at baseline and the two follow-up points.

The researchers write that different tadalafil dosing schedules or prophylaxis with another phosphodiesterase-5 inhibitor in a larger study may prove effective, but note that previous studies have also failed to show a significant preventive effect.

“[B]ased on evidence available presently, there is no support for phosphodiesterase-5 inhibitor use to prevent ED after highly conformal external radiotherapy or low-dose-rate brachytherapy”, they conclude.

“Alternative strategies to prevent ED in this context appear warranted, perhaps with attention toward alternative dosing, investigation of neuroprotective interventions, or further refinements of radiotherapy delivery methods.”


Pisansky T, Pugh S, Greenberg R, et al. Tadalafil for prevention of erectile dysfunction after radiotherapy for prostate cancer. The Radiation Therapy Oncology Group [0831] randomized clinical trial. JAMA 2014; 311:1300–1307. doi:10.1001/jama.2014.2626

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