An update on the current status and future prospects of erectile dysfunction following radical prostatectomy

BACKGROUND

Radical prostatectomy (RP) and radiation treatment are standard options for localized prostate cancer. Even though nerve-sparing techniques have been increasingly utilized in RP, erectile dysfunction (ED) due to neuropraxia remains a frequent complication. Erectile function recovery rates after RP remain unsatisfactory, and many men still suffer despite the availability of various therapies.

OBJECTIVE

This systematic review aims to summarize the current treatments for post-RP-ED, assess the underlying pathological mechanisms, and emphasize promising therapeutic strategies based on the evidence from basic research.

METHOD

Evaluation and review of articles on the relevant topic published between 2010 and 2021, which are indexed and listed in the PubMed database.

RESULTS

Phosphodiesterase type 5 inhibitors, intracavernosal and intraurethral injections, vacuum erection devices, pelvic muscle training, and surgical procedures are utilized for penile rehabilitation. Clinical trials evaluating the efficacy of erectogenic drugs in this setting are conflicting and far from being conclusive. The use of androgen deprivation therapy in certain scenarios after RP further exacerbates the already problematic situation and emphasizes the need for effective treatment strategies.

CONCLUSION

This article is a detailed overview focusing on the pathophysiology and mechanism of the nerve injury developed during RP and a compilation of various strategies to induce cavernous nerve regeneration to improve erectile function (EF). These strategies include stem cell therapy, gene therapy, growth factors, low-intensity extracorporeal shockwave therapy, immunophilins, and various pharmacological approaches that have induced improvements in EF in experimental models of cavernous nerve injury. Many of the mentioned strategies can improve EF following RP if transformed into clinically applicable safe, and effective techniques with reproducible outcomes.

Multifaceted Sexual Dysfunction in Dialyzing Men and Women: Pathophysiology, Diagnostics, and Therapeutics

Patient survival continues to increase with the growing quality of dialysis and management of chronic kidney disease (CKD). As such, chronic therapy must include considerations of quality of life (QOL), and this includes the disproportionate prevalence of sexual dysfunction (SD) in this patient population. This review aims to describe the pathophysiological and the psychosocial causes of SD with regard to renal replacement therapy, particularly hemo- and peritoneal dialysis. The differences in its manifestation in men and women are compared, including hormonal imbalances—and therefore fertility, libido, and sexual satisfaction—the experience of depression and anxiety, and QOL. The impact of comorbidities and the iatrogenic causes of SD are described. This review also presents validated scales for screening and diagnosis of SD in CKD patients and outlines novel therapies and strategies for the effective management of SD. Increased prevalence of CKD invariably increases the number of patients with SD, and it is crucial for health care professional teams to become familiar with the clinical tools used to manage this sensitive and under-quantified field. As a known predictor of QOL, sexual function should become a point of focus in the pursuit of patient-centered care, particularly as we seek to achieve as “normal” a life as possible for individuals who receive dialysis.

Erythropoietin to Enhance Recovery of Erectile Function in Men Following Radical Prostatectomy: The ERECT Trial

Erythropoietin receptors have been localized to human penile tissue and periprostatic neurovascular bundles. ERECT is a placebo-controlled, phase 2, randomized trial assessing the effect of erythropoietin on recovery of erectile function for men undergoing radical prostatectomy for prostate cancer.

Dipyridamole reduces penile apoptosis in a rat model of post-prostatectomy erectile dysfunction

Purpose:

Despite the nerve-sparing technique, many patients suffer from erectile dysfunction after radical prostatectomy (RP) due to cavernous nerve injury. The aim of this study was to evaluate dipyridamole as a potential treatment agent of post-radical prostatectomy erectile dysfunction.

Material and methods:

A total of 18 male Sprague-Dawley rats were randomized into three experimental Groups (SHAM+DMSO, BCNI+DMSO and BCNI+DIP). An animal model of bilateral cavernous nerve crush injury (BCNI) was established to mimic the partial nerve damage during nerve-sparing RP. After creating of BCNI, dimethyl sulphoxide (DMSO) was administered transperitoneally as a vehicle to SHAM+DMSO and BCNI+DMSO Groups. BCNI+DIP Group received dipyiridamole (10mg/kg/day) as a solution in DMSO for 15 days. Afterwards, rats were evaluated for in vivo erectile response to cavernous nerve stimulation. Penile tissues were also analyzed biochemically for transforming growth factor-β1 (TGF-β1) level. Penile corporal apoptosis was determined by TUNEL method.

Results:

Erectile response was decreased in rats with BCNI and there was no significant improvement with dipyridamole treatment. TGF-β1 levels were increased in rats with BCNI and decreased with dipyridamole treatment. Dipyridamole led to reduced penile apoptosis in rats with BCNI and there was no significant difference when compared to sham operated rats.

Conclusions:

Although fifteen-day dipyridamole treatment has failed to improve erectile function in rats with BCNI, the decline in both TGF-β1 levels and apoptotic indices with treatment may be helpful in protecting penile morphology after cavernous nerve injury.

Neuroprotective and Nerve Regenerative Approaches for Treatment of Erectile Dysfunction after Cavernous Nerve Injury

Erectile dysfunction (ED) is a significant cause of reduced quality of life in men and their partners. Cavernous nerve injury (CNI) during pelvic surgery results in ED in greater than 50% of patients, regardless of additional patient factors. ED related to CNI is difficult to treat and typically poorly responsive to first- and second-line therapeutic options. Recently, a significant amount of research has been devoted to exploring neuroprotective and neuroregenerative approaches to salvage erectile function in patients with CNI. In addition, therapeutic options such as neuregulins, immunophilin ligands, gene therapy, stem cell therapy and novel surgical strategies, have shown benefit in pre-clinical, and limited clinical studies. In the era of personalized medicine, these new therapeutic technologies will be the future of ED treatment and are described in this review.

Current rehabilitation strategy: clinical evidence for erection recovery after radical prostatectomy

Erectile function (EF) recovery remains a prominent functional outcome underachievement of radical prostatectomy (RP), despite the success of anatomic “nerve-sparing” technique and its recent refinements in the modern surgical era. Delayed (for as much as a few years) or incomplete (partial and unusable) EF recovery commonly occurs in many men still today undergoing this surgery. “Penile rehabilitation”, alternatively termed “EF rehabilitation”, originated formally as a therapeutic practice approximately 15 years ago for addressing post-RP erectile dysfunction (ED) beyond conventional ED management. Although the premise of this therapy is conceptually sound and generally accepted, in reference to the implementation of strategies for promoting EF recovery to a naturally functional level in the absence of erectile aids (distinct from the premise of conventional ED management), the optimal manner and efficacy of currently suggested therapeutic strategies are far less established. Such strategies include regimens of standard ED-specific therapies (e.g., oral, intracavernosal, and intraurethral pharmacotherapies; vacuum erection device therapy) and courses of innovative interventions (e.g., statins, erythropoietin, angiotensin receptor blockers). An endeavor in evolution, erection rehabilitation may ideally comprise an integrative program of sexual health management incorporating counseling, coaching, guidance toward general health optimization and application of demonstrably effective “rehabilitative” interventions. Ongoing intensive discovery and rigorous investigation are required to establish efficacy of therapeutic prospects that fulfill the intent of post-RP erection rehabilitation.

Penile rehabilitation after pelvic cancer surgery

Erectile dysfunction is the most common complication after pelvic radical surgery. Rehabilitation programs are increasingly being used in clinical practice but there is no high level of evidence supporting its efficacy. The principle of early penile rehabilitation stems from animal studies showing early histological and molecular changes associated with penile corporal hypoxia after cavernous nerve injury. The concept of early penile rehabilitation was developed in late nineties with a subsequent number of clinical studies supporting early pharmacologic penile rehabilitation. These studies included all available phosphodiesterase type 5 inhibitors, intracavernosal injection and intraurethral use of prostaglandin E1 and to lesser extent vacuum erectile devices. However, these studies are of small number, difficult to interpret, and often with no control group. Furthermore, no studies have proven an in vivo derangement of endothelial or smooth muscle cell metabolism secondary to a prolonged flaccid state. The purpose of the present report is a synthetic overview of the literature in order to analyze the concept and the rationale of rehabilitation program of erectile dysfunction following radical pelvic surgery and the evidence of such programs in clinical practice. Emphasis will be placed on penile rehabilitation programs after radical cystoprostatectomy, radical prostatectomy, and rectal cancer treatment. Future perspectives are also analyzed.

Preoperative erythropoietin administration in patients with prostate cancer undergoing radical prostatectomy without transfusion

Purpose

In this study, we administered erythropoietin preoperatively to patients who underwent open radical prostatectomy without transfusion to increase their hemoglobin levels and investigated the efficacy of this procedure.

Materials and Methods

We evaluated 62 patients who underwent open radical prostatectomy performed by the same surgeon between June 2005 and January 2011. The 22 patients who refused transfusion were assigned to group 1; the patients who accepted transfusion were assigned to group 2. Before surgery, we administered erythropoietin beta to group 1 patients whose hemoglobin levels were <12 g/dL and retrospectively compared the clinical data of the two groups. We used the t-test and the chi-square test for statistical analysis.

Results

Mean preoperative hemoglobin levels in group 1 after erythropoietin administration (14.5 g/dL) were significantly higher than those in group 2 (13.59 g/dL, p=0.003). Moreover, the difference in the mean hemoglobin levels before and after surgery for group 1 patients (3.55 g/dL) significantly exceeded that for group 2 patients (2.08 g/dL, p=0.000). Additional analysis revealed no statistically significant differences in perioperative complications between the groups.

Conclusions

Preoperative erythropoietin administration increased the safety margin of hemoglobin levels, and this strategy worked sufficiently well in our experience.

Optimizing postoperative sexual function after radical prostatectomy

Erectile dysfunction (ED) is one of the complications associated with pelvic surgery. The significance of ED as a complication following pelvic surgery, especially radical prostatectomy (RP), lies in the negative impact that it has on patients' sexual and overall life. In the literature, rates of ED following RP range from 25% to 100%. Such variety is associated with pelvic dissection and conservation of neurovascular structures. Another important factor impacting on postoperative ED is the preoperative erectile function of the patient. Advances in the knowledge of pelvic anatomy and pathological mechanisms led to a refinement of pelvic surgical techniques, with attention to the main structures that if damaged compromise erectile function. These improvements resulted in lower postoperative ED rates and better erectile recovery, especially in patients undergoing RP. Furthermore, surgery alone is not sufficient to prevent this complication, and thus, several medical strategies have been tested with the aim of maximizing erectile function recovery. Indeed it seems that prevention of postoperative ED must be addressed by a multimodal approach. The aim of this review is to give a picture of recent knowledge, novel techniques and therapeutic approaches in order to reach the best combination of treatments to reduce the rate of ED after pelvic surgery.

Erectile preservation following radical prostatectomy

Prostate cancer is the most common cancer among men, representing approximately 25% of all new cancer diagnoses in the USA. For clinically localized prostate cancer, the gold standard for therapy remains radical prostatectomy. One of the main adverse effects of this procedure is erectile dysfunction, which can have a significant impact on the patient's quality of life. There are several mechanisms of erectile dysfunction postprostatectomy, including arteriogenic, venogenic and neurogenic types, as well as the potentially heightened risk of postprostatectomy patients to develop Peyronie's disease. The purpose of this review is to explain the various treatment options available, including phosphodiesterase type 5 inhibitors, intracavernosal injections, intraurethral alprostadil suppositories, vacuum erection devices, and penile prostheses. The role of these therapies in an erectile-dysfunction-treatment function, as well as in penile rehabilitation, will be discussed. Finally, a review of research on novel therapies will also be presented. A comprehensive literature review was performed using the PubMed database. Articles were chosen based on topical relevance and assessed for methodology and major findings. There are data to support the use of each of the therapeutic options in both treatment and rehabilitative roles. More study is needed, however, specifically in regard to penile rehabilitation, to confirm its benefits, as well as to determine optimal rehabilitation protocols.

Future sexual medicine physiological treatment targets

INTRODUCTION

Sexual function in men and women incorporates physiologic processes and regulation of the central and peripheral nervous systems, the vascular system, and the endocrine system. There is need for state-of-the-art information as there is an evolving research understanding of the underlying molecular biological factors and mechanisms governing sexual physiologic functions.

AIM

To develop an evidence-based, state-of-the-art consensus report on the current knowledge of the major cellular and molecular targets of biologic systems responsible for sexual physiologic function.

METHODS

State-of-the-art knowledge representing the opinions of seven experts from four countries was developed in a consensus process over a 2-year period.

MAIN OUTCOME MEASURES

Expert opinion was based on the grading of evidence-based medical literature, widespread internal committee discussion, public presentation, and debate.

RESULTS

Scientific investigation in this field is needed to increase knowledge and foster development of the future line of treatments for all forms of biological-based sexual dysfunction. This article addresses the current knowledge of the major cellular and molecular targets of biological systems responsible for sexual physiologic function. Future treatment targets include growth factor therapy, gene therapy, stem and cell-based therapies, and regenerative medicine.

CONCLUSIONS

Scientific discovery is critically important for developing new and increasingly effective treatments in sexual medicine. Broad physiologic directions should be vigorously explored and considered for future management of sexual disorders.