Mohit Khera, MD, presented “Preserving Erectile Function After Radiation and Surgery” during the Southwest Prostate Cancer Symposium on April 15, 2018 in Scottsdale, Arizona.
How to cite: Khera, Mohit. “Preserving Erectile Function After Radiation and Surgery” April 15, 2018. Accessed [date today]. https://grandroundsinurology.com/preserving-erectile-function-after-radiation-and-surgery/
Preserving Erectile Function After Radiation and Surgery – Summary
Mohit Khera, MD, MBA, MPH, the secretary of the Sexual Medicine Society of North America, explains the importance of implementing penile rehabilitation and erectile preservation programs early following radical prostatectomy (RP). He reviews the literature regarding PDE5 inhibitors, followed by vacuum erection devices (VED), intracavernosal injection therapy, and urethral suppositories. Furthermore, he discusses the possibility of adopting adipose-derived stem cells and shockwave therapy in this setting.
Penile Rehabilitation Patterns Amongst Urologists
The American Urological Association (AUA) conducted a survey to assess penile rehabilitation patterns following RP among urologists. Out of 618 urologists who completed the study, a majority reported they do perform a penile rehabilitation program.
The majority of these urologists also started rehabilitation immediately or within less than four months after surgery, and that rehabilitation lasted for 12 to 24 months. Throughout this presentation, Dr. Khera stresses the importance of implementing penile rehabilitation and erectile preservation programs early post-RP.
Are We Implementing Erectile Preservation too Late After Prostatectomy?
Although the penile tissue remains healthy immediately post-RP, the incidence of venous leak is 14% at 4 months, 30% at 8 months, and 50% at 12 months. This is because in the absence of rehabilitation methods, RP-associated neurapraxia causes atrophy of the penile tissue. The goal of erectile preservation is to prevent cavernosa tissue damage that occurs during the period of neural recovery.
John Mulhall, MD conducted a study to determine predictors of post-RP erectile recovery. The study showed patients who underwent non-nerve-sparing procedure, received TriMix doses higher than 0.50cc prior to surgery, were over the age of 60, had one or more vascular comorbidity, and most importantly, began penile rehabilitation 6 months or later post-RP were at the highest risk of failure for return of natural erections. Therefore, it is essential urologists begin penile rehabilitation programs early post-RP.
A study by Iacono et al. showed that without any form of penile rehabilitation post-RP, at 2 months. Patients had significant decrease in the corporal smooth muscle and elastic fibers and increase in collagen. At 12 months, there was a 60% increase in collagen and a 65% decrease in elastic fibers in the smooth muscle. This further illustrates the importance of preserving penile tissue health directly after RP.
Comparing Management Options for Erectile and Penile Tissue Preservation
In order to preserve penile tissue and health, post-RP patients should experience at least three erections a week. This is because the penis is chronically in a hypoxic state, and intercourse or nocturnal erections provide blood flow. Dr. Khera analyzes the literature regarding PDE5 inhibitors (including sildenafil, tadalafil, and vardenafil) and intracavernosal injections their ability to potentiate these erections.
The greatest benefit of VED is preserving, and in some cases improving, penile muscle length and girth. However, vacuums predominantly pulls venous blood into the tissue, while arterial blood is optimal for tissue preservation.
Additionally, alprostadil (MUSE) is limited in its benefits to erectile function. As it is an urethral suppository, it may not cross into the cavernosa body.
The Female Factor
Patient compliance is a major factor in the efficacy of these rehabilitation programs. Financial cost and frustration often lead to patient noncompliance.
Dr. Khera and a research group published a study in The Journal of Sexual Medicine showing that patients with intimate partners comply with erectile preservation therapy better than those without partners.
Future Novel Therapies
Although no definitive cure of erectile dysfunction (ED) exists, adipose-derived stem cells and shockwave therapy have showed promise in recent years .
Data from animal models is favorable toward using adipose-derived stem cells to recover erectile function, prevent smooth muscle atrophy, prevent fibrosis, and improve nerve conduction. Dr. Khera summarizes the four published clinical trials testing stem cell efficacy in ED in this presentation.
Shockwave therapy recruits stem cells, activates resident stem cells and nerve repair, and significantly improves endothelial function. The rationale behind shockwave therapy as a modality for ED is that angiogenic properties stimulate neovascularization, increasing blood flow into the penile tissue. Many studies show shockwave therapy converting PDE5 inhibitor non-responders to responders. With further research, this could be a promising ED treatment modality.