The association between preoperative multiparametric MRI-defined prostatic apex shape and urinary continence recovery after radical prostatectomy: a systematic review and meta-analysis of comparative studies.

Introduction
Prostate cancer constitutes a major global health challenge as the second most diagnosed malignancy in men, with over 1.4 million new cases annually worldwide [1]. For patients with localized disease, radical prostatectomy (RP) remains the gold-standard curative treatment, demonstrating superior oncologic outcomes compared to radiation or active surveillance [2]. Despite advancements in surgical techniques (e.g., robotic-assisted approaches), postoperative complications significantly impact quality of life. Among these, urinary incontinence (UI) is particularly prevalent, affecting 20–87% of patients at 3 months and persisting in 5–20% beyond 12 months [3]. This functional impairment frequently leads to social withdrawal, depression, and increased healthcare utilization [4].
Multiple perioperative factors influence urinary continence recovery, including patient age, body mass index, surgical approach, and nerve-sparing status [5]. Anatomic predictors identifiable on preoperative multiparametric-MRI (mp-MRI) have recently gained prominence. Although membranous urethral length (MUL) remains a recognized predictor [6], the configuration of the prostatic apex (overhanging, parallel, or anteriorly angled) is a key morphological feature that directly determines surgical dissection planes. An overhanging apex may necessitate extensive sphincter manipulation during apical dissection, potentially compromising urethral support structures [7].
However, the relationship between MRI-defined prostatic apex shape and urinary continence recovery remains controversial [8]. Methodological heterogeneity in apex classification and urinary continence definitions contributes to these discrepancies [3, 6]. This systematic review and meta-analysis quantitatively synthesizes evidence regarding preoperative mpMRI-defined prostatic apex shape and urinary continence recovery after RP.

Materials and methods
This study adhered to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) and AMSTAR (Assessing the Methodological Quality of Systematic Reviews) guidelines for systematic reviews and meta-analyses [9, 10]. Because our research involved the synthesis of already available data from previously published studies, it was exempt from the need for ethical approval or patient consent.

Literature search
A comprehensive and systematic literature search was performed to identify all relevant studies investigating the association between prostatic apex shape on preoperative mp-MRI and recovery of urinary continence after RP. The electronic databases MEDLINE (via PubMed), Cochrane Library, Web of Science, and Embase were systematically searched from inception until November 1, 2025. The search strategy was developed in collaboration with an experienced medical librarian and utilized a combination of controlled vocabulary terms (e.g., MeSH in MEDLINE, Emtree in Embase) and free-text keywords related to three core concepts: (1) prostate cancer or radical prostatectomy, (2) prostatic apex or apical anatomy, and (3) urinary continence or incontinence. Search terms were adapted to the specific syntax and indexing rules of each database. The complete search strategy for PubMed/MEDLINE is provided in Appendix S1. No restrictions were applied regarding language or publication status to minimize the risk of selection bias. In addition, the reference lists of all included articles and relevant review papers were manually screened to identify any potentially eligible studies not captured by the electronic database search. The study selection process, including title/abstract screening and full-text eligibility assessment, was performed independently by two investigators. Any discrepancies between reviewers were resolved through discussion until a consensus was reached.

Inclusion and exclusion criteria
Two researchers independently screened the titles and abstracts of all retrieved records to exclude obviously irrelevant studies, with reasons for exclusion documented. The full texts of potentially relevant articles were then thoroughly evaluated against the predefined eligibility criteria. The inclusion criteria were: (1) original comparative studies (prospective or retrospective cohort or case-control designs) evaluating the association between preoperative mp-MRI-defined prostatic apex shape and urinary continence recovery after RP (including open, laparoscopic, or robot-assisted approaches); (2) studies that provided quantifiable comparative data, such as hazard ratios (HRs), odds ratios (ORs), or sufficient raw data for the calculation of these effect measures, with corresponding 95% confidence intervals (CIs); (3) studies that clearly classified the prostatic apex shape using the predefined Lee classification system (Types A, B, C, and D). Exclusion criteria comprised non-comparative studies, case reports, review articles, editorials, conference abstracts, comments, studies with overlapping patient populations, and publications lacking essential data for meta-analysis. For duplicate publications originating from the same cohort, the most recent or the most methodologically robust and comprehensive version was selected. Any disagreements that arose during the screening or selection process were resolved through discussion between the two reviewers until a consensus was reached.

Data extraction and methodological quality assessment
Two reviewers independently extracted data from each eligible study using a predefined, piloted data extraction form in Microsoft Excel. The extracted information included first author, publication year, country, study design, sample size, patient demographics, surgical approach (open, laparoscopic, or robot-assisted), method of prostatic apex shape assessment on mp-MRI, Lee classification type distribution, definition and measurement of urinary continence recovery, and reported effect estimates (hazard ratios, odds ratios, or raw data with confidence intervals). All included studies evaluated continence recovery as a time-to-event outcome, using Kaplan–Meier survival analysis and Cox proportional hazards models. Hazard ratios (HRs) were therefore extracted as the primary measure of association, reflecting the likelihood of earlier continence recovery over the postoperative follow-up period. If critical data were missing or unclear, the corresponding authors of the original studies were contacted via email to request additional information. Any discrepancies between the two reviewers during data extraction were resolved through iterative review and discussion until a full consensus was reached.
The methodological quality of the included non-randomized studies was independently assessed by two investigators using the Newcastle-Ottawa Scale (NOS) [11]. The NOS evaluates studies across ten domains related to selection, comparability, and outcome assessment. Each item was scored as “1” if clearly satisfied or “0” if not met or not reported. Total scores ranged from 0 to 10, with studies categorized as having high (8–10), moderate (5–7), or low (≤ 4) quality. In cases of scoring discrepancies, the two assessors engaged in structured deliberation to align their interpretations, consulting a third senior researcher when necessary to ensure consistent and criterion-based evaluation.

Data synthesis and analysis
The risk evaluation for every included study was calculated by employing HRs along with their 95% CIs using STATA software (Serial number: 10699393; StataCorp Wyb). The search strategy and literature screening process were illustrated through a PRISMA-compliant flowchart. Study outcomes and their variations were graphically represented using forest plots. Heterogeneity assessment was performed through the I² statistic, where different values indicated varying levels of study inconsistency. Following Cochrane recommendations [12], studies demonstrating I² values ≥ 50% were analyzed using a random effects model, while those below this threshold employed a fixed-effects approach. Statistical significance was determined at P < 0.05. To explore methodological and demographic influences on heterogeneity, subgroup analyses were performed according to different regions and study designs. Sensitivity testing involved systematic exclusion of individual studies to verify result stability. Potential heterogeneity sources were investigated through meta-regression using restricted maximum likelihood estimation, with log odds ratio as the independent variable and study characteristics (study design and geographic location) as covariates. Regression significance was evaluated through p-values. Publication bias was assessed visually using funnel plots and formally evaluated with Egger’s test [13].

Results

Study identification and selection
The initial database search yielded a total of 958 records. Following the removal of 337 duplicates, 621 unique records underwent title and abstract screening. Of these, 608 publications were excluded as they did not meet the predefined eligibility criteria. The remaining 13 articles underwent full-text assessment for eligibility. After detailed evaluation, 6 studies were excluded with reasons: 2 for having irrelevant outcomes, 1 for being non-comparative study, and 3 due to insufficient data for meta-analysis. Ultimately, 7 studies [14–20] comprising a total of 4,669 patients were included in the quantitative synthesis. The study selection process, including reasons for exclusion at each stage, is detailed in the PRISMA flow diagram (Fig. 1).

Study characteristics
The baseline characteristics of the included studies are presented in Table 1. The present meta-analysis included a total of seven comparative studies, published between 2006 and 2025, encompassing 4,669 patients who underwent RP. The studies were conducted across three countries: Italy (n = 2), Germany (n = 2), and Korea (n = 3). Study designs comprised four retrospective and three prospective cohorts. All studies utilized preoperative multiparametric MRI to classify prostatic apex shape according to the Lee classification system (Types A–D), and all defined urinary continence recovery as the use of zero or one safety pad per day. Surgical approaches varied among the studies, including robot-assisted radical prostatectomy (RARP), open retropubic prostatectomy (ORP), laparoscopic radical prostatectomy (LRP), and mixed approaches. Baseline patient characteristics were generally consistent across studies. The mean age ranged from 64 to 68.5 years, mean BMI (Body Mass Index) values were between 24.2 and 26.9 kg/m², and preoperative PSA levels varied from 7.0 to 13.1 ng/mL. Sample sizes per Lee type were reported in each study, with Type A serving as the reference category for all hazard ratio comparisons. The reported HRs with 95% CIs for urinary continence recovery were extracted for Types B, C, and D relative to Type A across all included studies. Although continence was defined uniformly as the use of zero or one safety pad per day, the timing of assessment varied across studies, with primary evaluations reported at 1, 3, 6, and 12 months. All studies employed time-to-event analysis, permitting the synthesis of HRs across different follow-up schedules.

Methodological quality assessment
The methodological quality of the included studies was rigorously evaluated using the NOS. Among the seven studies analyzed, six were rated as high quality, with scores ranging from 8 to 9 [14–17, 19, 20]. One study was graded as moderate quality, with a score of 6 [18]. The consistently high scores across most studies reflect robust methodological design, particularly in patient selection, comparability of cohorts, and outcome assessment.

Meta-analysis of preoperative prostatic apex shape and postoperative urinary continence recovery after RP
A total of seven cohort studies, encompassing 4,669 patients, were included in this meta-analysis. The synthesized results demonstrated that a Lee type D prostatic apex was significantly associated with earlier recovery of urinary continence following RP, with a pooled HR of 1.31 (95% CI: 1.16–1.48; p < 0.001). Given the low heterogeneity among the studies (I² = 20.7%), a fixed-effect model was employed for this comparison (Fig. 2). In contrast, no statistically significant associations were observed for either type C (HR = 1.01, 95% CI: 0.85–1.20; p = 0.897; Fig. 3) or type B (HR = 0.94, 95% CI: 0.81–1.09; p = 0.411; Fig. 4) when each was compared against type A as the reference.

To further elucidate the influence of study design and geographical variations, pre-specified subgroup analyses were conducted for the Lee type D comparison. Consistent and statistically significant associations were maintained across all subgroups. Among retrospective studies, the pooled HR was 1.27 (95% CI: 1.12–1.44), while a stronger effect size was observed in prospective studies (HR = 1.94, 95% CI: 1.23–3.07). Similarly, subgroup analysis stratified by country revealed significant results within each regional cohort: Italy (HR = 1.28, 95% CI: 1.11–1.49), Germany (HR = 1.28, 95% CI: 1.03–1.61), and Korea (HR = 2.18, 95% CI: 1.56–4.11) (Table 2). These findings suggest the prognostic value of the type D apex is robust across different methodologies and populations.

Sensitivity analysis, performed by iteratively excluding individual studies, confirmed that no single study unduly influenced the overall pooled estimate, supporting the stability and reliability of our results (Fig. 5). To explore potential sources of heterogeneity, meta-regression was conducted using study design and country as covariates. Neither variable significantly contributed to between-study variance (p = 0.202 for study design; p = 0.320 for country), corroborating the consistency of the primary findings. Furthermore, Egger’s regression test indicated no significant publication bias (p = 0.131), suggesting that the included studies represent a unbiased sample of the available evidence.

Discussion

Main findings
This systematic review and meta-analysis comprehensively evaluated the association between preoperative multiparametric MRI-defined prostatic apex shape and recovery of urinary continence following RP. The pooled results from seven comparative studies demonstrated a statistically significant correlation between a Lee type D apical morphology and earlier recovery of urinary continence, with a hazard ratio of 1.31. In contrast, no significant associations were identified for type B or C apex shapes when compared to type A. Subgroup analyses further confirmed the consistency of this association across different study designs and geographical regions. Sensitivity analysis underscored the robustness of the primary outcome, as the effect estimate remained stable upon sequential exclusion of individual studies. Meta-regression indicated that neither study design nor country of origin significantly contributed to the observed heterogeneity. Additionally, no substantial publication bias was detected, supporting the reliability of the synthesized evidence.

Implications for clinical practice
Urinary continence recovery following RP remains a clinically significant challenge with multifactorial determinants. Anatomical factors are paramount, where preoperative MUL serves as a critical predictor. Surgical technique exerts an equally profound influence, particularly nerve-sparing approaches that preserve autonomic innervation [21]. It is important to note that reported continence rates can vary substantially based on the definition used (e.g., pad-free status vs. 0–1 safety pad per day) and the surgical approach. A recent matched-pair analysis comparing robotic-assisted and retropubic RP underscored that differences in continence definitions and technical modalities can significantly influence functional outcome assessments, highlighting the need for standardized reporting [22]. Patient-specific variables further modulate outcomes. While younger age is often associated with enhanced neuromuscular recovery potential, contemporary evidence suggests that chronological age alone may not be a predominant risk factor for incontinence, with anatomical and surgical factors playing a more decisive role [23]. Conversely, preoperative lower urinary tract symptoms (LUTS) may indicate compromised baseline sphincter function [17]. The interplay between these elements—ranging from intrinsic pelvic anatomy to surgical precision—explains why continence recovery timelines remain variable despite decades of procedural refinements.
The morphological configuration of the prostatic apex, as delineated by mp-MRI, influences continence outcomes through four interconnected biomechanical pathways. Primarily, an anteriorly or posteriorly “covered” apex (overhanging > 50% of urethral circumference) obscures visualization during apical dissection, increasing iatrogenic injury risk to the external urethral sphincter and its delicate neurovascular supply [18]. Crucially, Tienza et al. demonstrated that covered apex configurations correlate with significantly shorter MUL measurements (mean difference: 2.9 mm; p < 0.001), directly reducing functional urethral reserve [24]. Third, the spatial relationship between apex and urethra dictates anastomotic tension; covered morphologies necessitate excessive traction during vesicourethral reconstruction, potentially compromising rhabdosphincter vascularization and neural feedback loops [25]. Finally, apex shape may reflect intrinsic pelvic floor variations—covered configurations associate with thinner periurethral endopelvic fascial layers that provide diminished structural support during tissue remodeling [26]. These mechanisms collectively explain the 3.2-fold higher early continence rates observed in patients with “uncovered” apex morphology where urethral margins remain fully exposed [18].
These pathoanatomical insights translate into tangible clinical protocols. Preoperatively, MRI-based apex classification (Lee classification) should dictate surgical strategy: for covered morphologies, surgeons should implement posterior rhabdosphincter reconstruction to augment urethral support [27], avoid thermal energy within 5 mm of the sphincter complex [28], and meticulously preserve puboprostatic ligaments to maintain urethral suspension [29]. Intraoperatively, real-time correlation of T2-weighted axial sequences with anatomical landmarks optimizes dissection depth at critical junctions [24]. Postoperatively, patients with covered apex morphology benefit from immediate (< 48 h post-catheter removal), therapist-supervised pelvic floor rehabilitation protocols, which demonstrate 33% superior continence recovery at 3 months versus standard care [30]. Crucially, preoperative counseling must incorporate apex morphology data—patients with covered configurations should be advised of probable 3–6 month continence recovery delays [31], while those with concurrent MUL < 10 mm may require expectation management regarding potential long-term pad usage [21].
In conclusion, prostatic apex shape represents a modifiable predictor whose impact transcends mere anatomical curiosity. Its effects cascade through urethral length preservation, sphincter integrity maintenance, and anastomotic precision optimization. Standardized MRI assessment should be integrated into preoperative algorithms to guide technical decisions, rehabilitation intensity, and expectation management. Future research must develop apex-specific predictive nomograms incorporating MUL, nerve-sparing extent, surgeon volume (> 500 cases), and racial variations—particularly given emerging evidence of slower continence recovery in Asian populations despite equivalent anatomical parameters [32]. Such precision medicine approaches will ultimately transform RP functional outcomes from unpredictable sequelae to engineered recoveries.

Strength and limitations
This meta-analysis represents the first comprehensive synthesis of evidence evaluating the association between preoperative multiparametric MRI-defined prostatic apex shape and urinary continence recovery after RP. By integrating data from multiple comparative studies across different regions, this work addresses a notable gap in urologic surgical research and offers valuable insights for preoperative counseling and surgical planning. Methodological rigor was maintained through a systematic literature search compliant with PRISMA guidelines, independent study selection and data extraction, and quality assessment using the NOS. The application of appropriate fixed- and random-effects models further enhances the reliability of the pooled estimates. These findings may contribute to improved preoperative risk stratification and personalized surgical decision-making.
Several limitations of this analysis deserve consideration. First, the inclusion of only seven studies limited the statistical power for subgroup comparisons and meta-regression, potentially leading to an underestimation of effect sizes or masking subtle associations. Although overall heterogeneity was low and not significantly influenced by study design or country according to meta-regression, other unmeasured confounding factors may contribute to variability in outcomes. A primary consideration is the variation in surgical technique and perioperative management across the included studies. Differences in surgical approach (e.g., robotic-assisted vs. open), the extent of nerve-sparing, surgeon experience and volume, methods of apical dissection, and perioperative rehabilitation protocols could all independently influence continence recovery timelines. While the original studies attempted to adjust for some of these factors, residual confounding cannot be entirely ruled out in this meta-analysis of observational data. The consistent association observed for the type D apex across different study designs and geographical regions, which encompass varied surgical practices, provides some reassurance regarding the robustness of this anatomical predictor. While we acknowledge that a subgroup analysis stratified by surgical approach would be highly informative, it was not feasible due to the limited number of included studies (n = 7) and the lack of sufficiently granular, technique-specific outcome data within them. Nevertheless, the inability to fully disentangle the effect of apex morphology from the potential influence of surgical technique remains a limitation of this synthesis. Furthermore, biological factors not captured by mp-MRI morphology, such as the presence of prostatic inflammation which has been linked to other postoperative outcomes, may also contribute to functional recovery variability, warranting investigation in future studies [33]. Furthermore, recent evidence suggests that prostate volume and morphological asymmetry may influence continence outcomes independently of apex shape [34]. The lack of stratified data on prostate size or asymmetry in the included studies precluded subgroup analysis on these factors. Future studies should consider integrating prostate volume and symmetry assessments to better elucidate their interplay with apical anatomy in continence recovery. Furthermore, detailed information regarding the timing of continence recovery was limited across the included studies, restricting our ability to perform a time-to-event analysis or evaluate the pace of functional recovery more granularly. Moreover, the use of HRs, while appropriate for time-to-event data, may limit direct comparability with studies using ORs for fixed time points, and we call for standardized outcome reporting in future research. Future studies should prioritize standardized and detailed reporting of continence outcomes at multiple postoperative timepoints to better elucidate the dynamic recovery process. Moreover, all included studies were observational in design, rendering them susceptible to residual confounding despite adjustments in original analyses. The generalizability of findings may also be constrained by geographic overrepresentation from only three countries. Future large-scale, prospective studies with standardized surgical reporting, longer follow-up, and detailed technical descriptions are needed to validate and extend these results.

Conclusion
Current evidence indicates that a Lee type D prostatic apex shape, as identified on preoperative multiparametric MRI, is significantly associated with earlier recovery of urinary continence following RP. This finding provides a valuable anatomical biomarker that may assist clinicians in preoperative patient counseling and personalized surgical planning. Future studies should also aim to standardize outcome reporting and explore the potential interaction between apical anatomy and surgical techniques to optimize functional outcomes.

Supplementary Information