Prostate cancer is the second most common cancer in men worldwide, affecting ~1.1 million men per year (1). Radical prostatectomy (rPR) and radiation beam therapy are comparable treatment options for localized prostate cancer (2) whereas treatment associated complications and incidences differ significantly.

Male stress urinary incontinence (SUI) has a predominantly iatrogenic cause after radical prostatectomy (3). It is defined by the complaint of involuntary leakage on effort or exertion or on sneezing, or coughing (4, 5). The mechanism for post-radical prostatectomy incontinence remains unclear (6), however, several hypothesis have been discussed. Despite direct injury to the internal sphincter itself, injury to the external rhabdosphincter or its shortened lengthwise (7), injuries to the supporting structures of the urethra (7), lesions to the nerve supply (6) or even detrusor underactivity (8) may impair continence.

The incidence of post-radical prostatectomy incontinence has become an increasingly common urological problem with a prevalence of 2.5–90% (9) depending on the definition for urinary continence. In a recent prospective non-randomized trial comparing open retropubic rPR and robotic assisted rPR including a total of 2,625 men, urinary incontinence defined by no change pad in 24 h after 12 month follow-up was 21.3 and 20.2% for robotic-assisted and open rPR, respectively (10). A meta-analysis did not identify a significant difference of urinary continence in comparison between open retropubic and robot assisted rPR (11, 12). A prospective randomized trial comparing laparoscopic and robotic-assisted rPR demonstrated significant better continence rates for robotic-assisted than laparoscopic rPR (95.0 vs. 83.3%) (13). A meta-analysis identified evidence for improved continence rates with robotic-assisted in comparison to laparoscopic rPR accordingly (14). Table 1 present the continence rates after radical prostatectomy reported by selected prospective trials.

Importantly, the impact of urinary incontinence to affected patients is substantial and include stigmatization and significant reduction of quality of life (20). In addition, the cost burden of urinary incontinence is currently estimated between $19 and $32 billion in the USA (9).

Overactive bladder (OAB), with or without urinary incontinence, can also occur after radical prostatectomy and is an underestimated cause for urinary incontinence after radical prostatectomy. However, so far there is a lack of robust data for its incidence.

In this non-systematic review, we provide an overview on pathophysiology and current treatment options of male stress urinary incontinence after radical prostatectomy.

There are different factors responsible for the post-rPR urinary incontinence. The most well-known factors include the changes that occur in the anatomy, the preoperative bladder function as well as the operation technique and the experience of the surgeon (21, 22). In addition, the anatomic support and the pelvic innervation have been identified as important contributors to post rPR continence (21). Among the many surgical and technical factors proposed in the literature as contributing to the development of urinary incontinence following rPR, extensive dissection during surgery, damage to the neurovascular bundle, and the development of postoperative fibrosis have a substantial negative impact on the continence status of men undergoing rPR. Sparing of the bladder neck and anterior, and possibly posterior, fixation of the bladder-urethra anastomosis are associated with better continence rates (22).

Continence is generally facilitated by the combination of the action of the detrusor muscle, the proximal intrinsic sphincter, the rhabdosphincter (23), and the urethral suspensory mechanism composed of pubourethral ligaments (24). After rPR, the proximal urethral sphincter, the suspensory ligaments as well as parts of the proximal intrinsic sphincter are removed. As a consequence, post rPR urinary continence is largely dependent on the rhabdosphincter (25). In addition, the pudendal nerve fibers that innervate the rhabdosphincter are damaged during the operation which has functional implications. This has been studied by transurethral ultrasound, that has shown thinning or atrophy as well as impaired contractility of the rhabdosphincter (25). Moreover, the innervation of the detrusor muscle and trigonum are impair which leads to a decreased detrusor contractility and poor bladder compliance (26, 27). The most predominant finding in urodynamic measurements is the sphincteric incontinence (28). On the other hand, intrinsic detrusor dysfunction and overactivity or impaired detrusor contractility, and altered detrusor compliance play a role in the post rPR continence (29). Preoperative urodynamic abnormalities have been observed to be present in 41% of patients, with half of them having detrusor overactivity (28).

About 50% of patients have preoperative impaired bladder compliance and impaired detrusor contractility and 47% de novo postoperative changes (30). Urodynamic studies carried out 1 year after rPR have shown sphincteric incontinence as the most common finding, which was responsible for about 88–100% urinary incontinence after rPR (26, 31, 32). About a third of the patients had an intrinsic sphincter deficiency as the single cause of their urinary incontinence (26, 32). Furthermore, detrusor overactivity and impaired bladder contractility were each found in up to a 30% of the cases (26, 32). However, in <9% of the cases, these findings were the only urodynamic finding (26, 32). In one out of five patients, bladder outlet obstruction was found, but this was the sole urodynamic finding in only 1% of the cases (31). Delayed first sensation (42%), mixed urgency-urge incontinence (48%), and decreased bladder capacity (< 300 mL) (41%) were the other findings on urodynamic measurements after rPR (26). It must also be stressed that, a highly well-established predictor of functional outcomes is the surgeon. It is well-known that patients treated in high volume centers and in experienced hands, are more likely to be dry. When reviewing different series, the absence of this variable could represent a limitation since, in some cases, an individual surgeon's outcomes may be much better, or worse, than any nomogram prediction. Better urinary continence recovery results can be expected by patients who undergo rPR performed by a surgeon with greater experience (33). An annual surgical case load of >50 cases/year results in improved continence recovery outcomes following rPR (33).

In the context of management of post-rPR OAB syndrome, it is important to understand its underlying pathophysiological mechanism (34). Since OAB is multifactorial (35), the exact role of prostate surgery in the development of OAB is still under debate as, after rPR, there are several variables that could contribute to detrusor overactivity.

Detrusor overactivity in patients after radical prostatectomy has been mainly attributed to a partial denervation of the bladder during surgery (30). However, together with bladder denervation, other hypotheses, such as the urethrovesical mechanism, have been described.

It has been demonstrated that urethral afferents are activated by urethral perfusion (36) and they could modulate the micturition reflex via pudendal and pelvic afferent and efferent signals, causing bladder contraction. This has been described as urethrovesical mechanism (37–39).

In a recent study, Mastukawa et al. identified that low maximum urethral closure pressure at baseline and its decrease postoperatively were strong predictors of de novo post-rPR OAB underlying the role of the intrinsic sphincter deficiency on the pathophysiology of OAB (40).

In contrast, detrusor underactivity may cause OAB syndrome as well, which seems contradictory at the first glance. Bladder underactivity may affect up to 40% of patients after radical prostatectomy mostly due to denervation (41).

Bladder outlet obstruction is a known cause of OAB. The obstruction after RP is mainly caused by bladder neck contracture and urethral stricture due to the anastomosis of the bladder neck with the urethra, which has an incidence up to 20% (42). BOO causes damage to the smooth muscle demonstrating histological changes in the bladder wall causing spontaneous myogenic contractions (43). Therefore, the presence of infravesical obstruction due to urethral stricture or bladder neck contracture must be excluded.

Damage to the urethral sphincter complex, the surrounding structures, or their innervation leads to higher rates of urinary incontinence after rPR. In addition, certain biological factors and parameters known preoperatively, including older age, higher BMI, pre-existing LUTS, lower motor unit lesion, and functional bladder changes, have been identified to have a negative impact on continence rates after rPR (22).

Recently, a preoperative model was presented to predict incontinence before rPR (Figure 1) (44). According this nomogram, high risk for biochemical recurrence, adjuvant radiotherapy, lower results in the validated quality of life questionnaire EORCT QLQ-C30/QoL, higher sum score of the validated questionnaire International Consultation of Incontinence Questionnaire—Urinary Incontinence—Short form (ICIQ-UI-SF) and higher patient age, were associated with statistically significant higher sum scores of the 12-month ICIQ-UI-SF, thus, representing higher impact of urinary incontinence (Figure 1) (44). Together with the preoperative model a new, postoperative nomogram was introduced to inform patients about the probability of an additional surgery for incontinence or, on the other hand, about the importance of enduring with a strict pelvic floor muscle training protocol (Figure 2) (44).

Interestingly, these results did not show any association with ICIQ-UI-SF, when including surgery volume (namely <50, 50–100, or >100 cases per year) (44).

R-squared (R²), the statistical measure that represents the proportion of the variance for a dependent variable, equalled 4% and 43% in the preoperative and postoperative models, respectively. This is mainly due to the retrospective nature of the study and to the intrinsic characteristics of the database (strict rules of the Belgian Cancer registry). The major drawback of this study, together with its retrospective nature, is that a single dataset has been used for development and validation of the model. Although a non-random splitting of the data is an acceptable design for evaluating model performance, external validation still has to be performed (42).

Prostate cancer is one of the most problematic and frequently encountered malignancies in male patients. It often occurs when men are still in the active period of their lives. Consequently, there is a high demand for minimally invasive therapeutic approaches, susceptible of preserving urinary continence and sexual function. Unfortunately, stress urinary incontinence is a common adverse event in men with localized or locally advanced prostate cancer undergoing radical prostatectomy, but also secondary to radiotherapy (external beam radiotherapy as well as brachytherapy) and to cryosurgery (73).

Despite rehabilitative procedures such as pelvic floor muscle training, biofeedback, electrical stimulation, lifestyle changes, or a combination of these strategies, no fully efficient treatment alternative has yet been established for this pathology (74). On the other hand, it should be acknowledged that nursing care, including the understanding of the patient's needs, education, and psychosocial support remain essential features while aiming to improve the quality of life of prostate cancer patients.

Concerning the newest experimental treatments made available for urinary incontinence subsequent to prostate cancer surgery, there are studies that have shown a significant improvement of continence after ultrasound guided injection of fibroblasts and myoblasts into the sphincter (75). Other clinical trials also emphasized encouraging outcomes provided by stem-cells injection into the rhabdosphincter (76). Last but not least, promising outcomes have been outlined as a result of intravesical Onabotulinum toxin A injection (77).

Most importantly, the therapeutic decision and the chosen treatment option must be individualized for each patient according to clinical and social factors. During the recent years, the development of new therapeutic choices such as male sling techniques provided a more acceptable management pathway for less severe forms of urinary incontinence related to radical prostatectomy. Following this perspective, technological improvements and the emergence of new dedicated devices currently create the premises for a continuously positive evolution of clinical outcomes in this particular category of patients.

MR: data collection, coordination and drafting the manuscript, and supervising. TM and TH: data collection, drafting the manuscript, and supervising. BG and MT: data collection and drafting the manuscript.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.