Prostate cancer is the second most common cancer affecting men. With recent advances in technology, surgical techniques using laparoscopic and robotic approaches are increasingly used to manage organ-confined prostate cancer.
In the current era of early prostate cancer detection, many younger, sexually active men are undergoing surgery and expressing concern about preservation of erectile function. Although urologists are using nerve-sparing techniques, complete recovery of erectile function after prostatectomy may take up to two years. Recent insights regarding the pathophysiology of postprostatectomy erectile dysfunction (ED) have sparked great interest in penile rehabilitation.
Rehabilitation programs involve the institution of prophylactic measures to improve cavernosal oxygenation, promote endothelial protection, and prevent cavernosal nerve injury-induced structural changes to promote early recovery of erectile function. In this article, we review the current treatment options for promoting and preserving sexual health after robotic-assisted laparoscopic radical prostatectomy (RALP).
Since 1998, phosphodiesterase-5 (PDE-5) inhibitors such as sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis), have been used as first-line therapy to treat ED. Because PDE-5 inhibitors are familiar to patients and easy to use, daily dosing has been advocated as initial therapy in penile rehabilitation.
The hypothesis is that daily PDE-5 inhibitor therapy promotes penile rehabilitation by stimulating smooth-muscle-cell replacement via a cyclic guanine monophosphate mechanism and by reducing collagen synthesis via phosphokinase G activation (Curr Urol Rep. 2009;10:219-225).
Recent prospective, randomized, controlled studies have shown the efficacy of daily sildenafil use. Bannowsky et al reported potency rates of 86% in the group using daily low-dose sildenafil compared with 66% of the control group (BJU Int. 2008;101:1279-1283). McCullough et al reported that men on daily sildenafil were five times more likely to experience return of spontaneous, unassisted erections sufficient for intercourse compared with placebo (J Sex Med. 2008;5:476-484).
However, results of a large randomized, placebo-controlled, double-blind, multicenter study evaluating nightly versus on-demand vardenafil showed no difference in efficacy (Eur Urol. 2008;54:204-210). Although this study showed that vardenafil was not effective for penile rehabilitation, whether the same conclusion can be drawn for sildenafil and tadalafil is unclear. Further studies comparing all PDE-5 inhibitors are warranted to determine the optimal dose, frequency, and specific type of PDE-5 inhibitor therapy needed to restore erectile function.
If PDE-5 inhibitor therapy is ineffective, alternative treatment options, such as intraurethral alprostadil suppository (MUSE) or intracorporeal injection therapy with vasoactive agents such as alprostadil, papaverine, and/or phentolamine, exist as second-line therapy.
These vasoactive agents increase blood flow into the cavernous sinuses locally either by increasing cyclic adenosine monophosphate levels, antagonizing alpha-adrenergic receptors, or acting directly on smooth-muscle relaxation. Success in the treatment of postprostatectomy ED has been reported in 57% of patients using intraurethral suppositories (J Urol. 1998;160:1325-1328) and in 67% of patients using intracorporeal injections (J Urol. 1997,158:1408-1410).
As part of a penile rehabilitation program in which intraurethral suppository or injection therapy was initiated within one week to three months after surgery, equal success has been observed in 74% of patients using intraurethral suppository (BJU Int. 2007;100:1317-1321) and 52% of patients using intracorporeal injection therapy (J Sex Med. 2005;2:532-540).
Although the most common reasons for discontinuing use were application difficulty and/or pain at the insertion or injection site, there appears to be a beneficial role for intraurethral suppository or intracorporeal injection therapy in a penile rehabilitation program.
For patients who cannot tolerate the side effects or who do not have a clinical response to these second-line noninvasive therapies, penile prosthesis implantation would be the next treatment option to consider. Penile prostheses have been available for the treatment of ED for 35 years. The inflatable penile prosthesis has the highest patient satisfaction rate (consistently higher than 90%) and the lowest mechanical revision rate (96% at 5 years, greater than 60% at 15 years) among virtually all medically implanted devices (Urol Clin North Am. 2007;34:535-547).
Postoperative infection is the most feared complication of prosthetic surgery, but the same study showed that introduction of antibiotic-coated prostheses has reduced infection rates to 1%. For the patient who is motivated and medically suitable for surgery, the penile prosthesis is a highly satisfying and effective treatment option for ED.