Nerve-SPARing Robotic Prostatectomy: The Impact of Patient Baseline Profiles on Erectile Function (SPARE-EF)

1. BACKGROUND AND RATIONALE Radical prostatectomy remains a cornerstone in the management of localized prostate cancer. With the advent and widespread adoption of robot-assisted radical prostatectomy (RARP), surgical precision has significantly improved. A critical component of RARP is the nerve-sparing (NS) technique-which can be performed unilaterally or bilaterally-aimed at preserving the delicate cavernous nerves responsible for erectile function.

   Despite advanced robotic visualization and microscopic dissection capabilities, post-operative erectile dysfunction (ED) remains a prevalent and distressing quality-of-life issue for patients. The success of functional recovery is not dictated by surgical technique alone; it is highly dependent on a complex interplay of pre-operative patient characteristics. Baseline erectile function, chronological age, metabolic comorbidities (such as diabetes, hypertension, and hyperlipidemia), smoking history, and psychiatric factors like baseline anxiety or depression heavily influence the neurovascular recovery cascade.

   Currently, clinicians lack a robust, individualized framework to accurately counsel patients on their specific probability of erectile function recovery when weighing their pre-operative risk profile against the planned degree of nerve sparing (unilateral vs. bilateral). Therefore, there is a critical need to systematically analyze how these baseline patient variables interact with the surgical technique to dictate long-term functional outcomes. This study seeks to bridge this gap, providing data-driven insights to optimize pre-operative patient counseling and manage post-prostatectomy expectations. In order to overcome the bias related to the experience and skill of the surgeon, all the NS RARP will be performed by one-single highly-trained robotic surgeon.

2. STUDY AIMS Primary Objective

   • To evaluate the quantitative value and clinical impact of unilateral and bilateral nerve-sparing techniques on the recovery of erectile function at 12 months post-RARP.
   • Creating a nomogram to predict erectile function at 12 months post- NS RARP Secondary Objectives
   • To identify and risk-stratify independent pre-operative predictors (e.g., age, baseline IIEF-5 scores, comorbidity indices) that significantly influence the trajectory of erectile recovery.
   • To compare the oncological safety (via positive surgical margin rates) of unilateral versus and nerve-sparing approaches in localized prostate cancer.
   • To assess the time-to-recovery dynamics of sexual function within the first year following surgery.
3. STUDY DESIGN General Architecture This is a unicentric, prospective, observational cohort study. Because the decision to perform unilateral, bilateral, or non-nerve-sparing surgery is dictated strictly by oncological safety, tumor characteristics (e.g., biopsy Gleason score, clinical stage, multiparametric MRI findings), and baseline patient anatomy, randomization is neither ethical nor feasible. Patients will be managed according to standard clinical pathways, and investigators will prospectively observe and record outcomes without interfering with the surgical strategy or post-operative rehabilitation protocols.

Surgeries will be performed by a single highly-experienced robotic surgeon with more than 5000 robotic procedures.

Patient Selection Criteria Inclusion Criteria

1. Age ≥ 18 and ≤ 75 years at the time of screening.
2. Histologically confirmed, clinically localized prostate cancer (cT1-cT2, Nx/0, Mx/0).
3. Candidates for robot-assisted radical prostatectomy (RARP) with a planned nerve-sparing approach (unilateral or bilateral) as determined by the attending urologist.
4. Patient is willing and able to complete validated quality-of-life questionnaires at baseline and during follow-up.
5. Signed informed consent prior to enrollment.

Exclusion Criteria

1. Pre-existing severe erectile dysfunction (baseline IIEF-5 score less than or equal to 7) unrelated to prostate cancer.
2. History of prior pelvic radiation, cryotherapy, or extensive pelvic surgery that disrupts neurovascular anatomy.
3. Neo-adjuvant androgen deprivation therapy (ADT) or chemotherapy.
4. Severe psychiatric or cognitive illness preventing reliable self-reporting. Data Collection & Follow-up Timeline Patients will be evaluated at four distinct time points: Baseline (Pre-operative), 3 months, 6 months, and 12 months post-operatively.

Evaluation Window Data/Variables to be Collected Baseline (Pre-operative) Demographics (Age, BMI), Comorbidities (Charlson Comorbidity Index), PSA, Biopsy Gleason, mpMRI stage, Baseline IIEF-5 score Intra-operative Degree of nerve sparing achieved (Extrafascial, Interfascial, Intrafascial), operative time, estimated blood loss, surgical margins.

3 & 6 Months Post-op IIEF-5 score, use of phosphodiesterase-5 inhibitors (PDE5-i) or intracavernosal injections, oncological status (PSA).

12 Months (End of Study) Final IIEF-5 score, return to baseline sexual function, total oncological control status, and margin analysis.

4. STUDY ENDPOINTS Primary Endpoint

• Erectile Function Recovery Rate at 12 Months: Defined as achieving an International Index of Erectile Function (IIEF-5) score >17 (or a return to within < 5 points of baseline score) at the 12-month post-operative mark, with or without the use of PDE5 inhibitors.

Secondary Endpoints

1. Potency Maintenance Over Time: Changes in the mean total IIEF-5 domain scores from baseline to 3 and 6 months post-RARP.
2. Oncological Safety Margins: The incidence of positive surgical margins (PSM) on final pathology, stratified by unilateral versus bilateral nerve-sparing cohorts.
3. Predictive Interaction Models: The statistical correlation weight between pre-operative comorbidity scores and the degree of nerve-sparing on 12-month potency rates.