Tadalafil ineffective for erectile dysfunction following prostate radiotherapy

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1. Radiotherapy for prostate cancer treatment often leads to erectile dysfunction. 

2. Daily tadalafil during treatment does not have protective effects against the development of erectile dysfunction. 

Evidence Rating Level: 1 (Excellent)     

Study Rundown: Prostate cancer therapy is one of the many causes of erectile dysfunction (ED) secondary to radiotherapy. Tadalafi, a phosphodiesterase-5 inhibitor, has been demonstrated to have a protective effect against penile tissue fibrosis and hypoxia therefore leading to the hypothesis that it may prevent ED following radiotherapy. The Radiation Therapy Oncology Group [O831] Trial sought to elicit the effect of daily tadalafil during and after radiotherapy through the first year post-treatment. It was found, with little ambiguity, that daily 5mg dosing of tadalafil for 24 weeks produced no difference in ED in the year following the start of external radiotherapy or brachytherapy. The strengths of this study lie in the large study population relative to past studies as well as the standardized course of therapy amongst participants. However, there was no variation in the daily 5mg dosing schedule, leaving the possibility that a different schedule may have produced significant results. At this point in the study of PDE-5 inhibitors for ED, there is little evidence to support their use as protective agents in prostate cancer treatment.

Click to read the study, published today in JAMA

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In-Depth [randomized controlled trial]: This study examined the effects of daily tadalafil treatment on the development of erectile dysfunction in patients undergoing radiotherapy for prostate cancer. Of the 242 participants who were randomized into a placebo group or treatment group, 109 control group patients and 112 tadalafil group patients were included in the primary analysis. The principal endpoint was ability to achieve maintained spontaneous erection 4-6 weeks after cessation of the 24 week daily 5mg tadafil therapy. At follow-up between 28-30 weeks, 79% of tadalafil patients and 74% of placebo patients (p=0.49) retained erectile function. At 1-year follow-up 72% of tadalafil patients and 71% of placebo patients (p=0.93) retained erectile function. After adjusting for radiotherapy type and age tadalafil showed no effect on erectile function between the patient groups (p= .24).

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