In Reply Although our study did not identify a role for tadalafil to prevent radiotherapy-related ED, Dr Castiglione and colleagues urge cautious interpretation of our results based on inadequate participant inclusion criteria and follow-up duration, and on possibly improper tadalafil administration. We do not agree that our participants’ favorable baseline (erectile function) profile negatively affected the trial’s outcome.
It is important to distinguish between penile rehabilitation after urological surgery (an ED preventive strategy after radiotherapy) and a therapeutic intervention for established ED. In the first, an acute vasogenic or neurogenic event (ie, radical prostatectomy) precipitates a sudden loss of function, from which recovery is sought—thus, rehabilitation. Radiotherapy-related injury to erectogenic tissue accumulates slowly and as a delayed response to treatment administered over several months—thus, a strategy seeking to prevent loss of existing function. We selected trial participants without ED because we sought to preserve spontaneous off-drug erectile function. Inclusion of participants with ED or with a significant burden of conditions contributing to its occurrence1 potentially would have confounded the results, lessening the opportunity to identify a treatment effect, and would have risked lack of generalization to the target population.
Pisansky TM, Bruner DW, Greenberg RE. Tadalafil for Erectile Dysfunction Prevention After Radiotherapy for Prostate Cancer—Reply. JAMA. 2014;312(7):748-749. doi:10.1001/jama.2014.7923