## 2 Materials and Methods  
The study was carried out in the University Clinical Center of Serbia, at the Clinic of Urology, Belgrade, between December 2014 and January 2020. The study had a prospective cohort design. The clinical and pathological data were collected from 170 consecutive patients diagnosed with PCa who underwent ORP and LRP in our institution. All radical prostatectomies were performed by one surgeon experienced in both laparoscopic and open approaches. Preoperative diagnostics included: prostate-specific antigen (PSA), digitorectal exam (DRE), computer tomography (CT) scan, bone scintigraphy, and, in some patients, magnetic resonance imaging (MRI). Pre-operative MRI was not performed routinely in this study. Of the 170 patients that participated in this investigation, 63 underwent ORP, while the remaining 107 underwent LRP. BNP was performed in 85 patients. BNP implies the preservation of the proximal aspect of the prostatic urethra as it joins the bladder neck. The selection criterion for performing BNP was the absence of a large prostatic median lobe. Patients with overgrowth of the median prostatic lobe into the bladder underwent bladder neck reconstruction, thus constituting the control (non-BNP) group. Before starting the dissection of the bladder neck, it is necessary to have an adequate orientation of its projection. We used three methods to identify the bladder neck. The simplest involves identifying the bladder neck by following the lateral edges of the prostate toward the expected location of the bladder neck. The second consists of identifying the bladder neck by pulling the balloon of the urinary catheter towards the base of the bladder, thus illustrating its projection. The third and perhaps the safest is based on the projection of the V-shaped fibrous tissue that extends from the puboprostatic ligaments, with the tip of the V directly above the projection of the bladder neck. During the dissection of the bladder neck, a combination of blunt preparation with a dissector, control of hemostasis with bipolar current, and cold resection with scissors was used. The urinary catheter is of great help when dissecting the neck, as it enables the precise detection of the frontal and lateral sides of the bladder neck. After freeing the frontal and lateral sides of the urethra, it is cut with scissors, thereby accessing the interior of the posterior wall of the bladder neck. After the dissection of the bladder neck described above, the urinary catheter is removed from the bladder, and a Ch18 Bougie is inserted in its place. With manipulation (elevation of the prostate using the Bougie), the posterior wall of the bladder neck is easily incised. Then, by blunt dissection, the base of the prostate is freed from the bottom of the bladder towards the seminal vesicles and the vas deferens. This method of preparation preserves the circular fibers of the bladder neck. After surgery, one expert uro-pathologist performed all macro-micro examinations on the prostate samples. The prostate specimen underwent standard formalin fixation following the Stanford protocol [11]. Information collected included: the pathologic stage of the tumor, Gleason score, the presence of PSMs, and lymph node invasion (pN). The specimens were preserved by soaking them for at least 24 h in buffered formalin before cutting. A more homogenous fixation was achieved by injecting formalin and sectioning a day later. The apex and base (bladder neck) were removed and divided into parasagittal or radial portions in our unit. The remainder of the material was split into transverse, 3-4 mm pieces cut perpendicular to the urethra's long axis. After quadrant sectioning, the resulting slices were implanted and processed as complete mounts [12]. Surgical margins were regarded as positive when cancer cells made contact with the surface of the radical prostatectomy specimen. Additionally, we divided PSM at five localizations: the base of the prostate, left and right lobes, both lobes, and the apex.