• SURGICAL TECHNIQUE
• ROBOT-ASSISTED RADICAL PROSTATECTOMY
• APICAL DISSECTION

Introduction & objective: Positive surgical margins (PSM) during robot assisted radical prostatectomy (RARP) are more frequent in apical region. Apical dissection is one of the most difficult steps in RARP since it affects not only cancer control but also continence recovery. We describe a novel approach for apical dissection, the collar technique.
Material & methods: We evaluated 189 consecutive patients treated with RARP between August 2015 and July 2016 at a single tertiary center, by a single experienced surgeon. Before RARP each patient underwent 3.0 T MRI. To assess the oncological and functional outcomes, we compared the patients treated between August and December 2015 (control group, 81 patients) with those operated between January and July 2016 (collar technique, 108 patients). Primary outcome was the rate of apical PSM. Secondary outcome included urinary continence recovery both at catheter removal and at 1,3,6 and 12 months. Continence was defined as the use of 0 or 1 safety pad per day. Brief description of the collar technique: the urethral sphincter complex is circumferentially incised 2-3 mm distally to the prostatic apex, in order to stay farther from the prostatic apex and avoid PSM; the underlying smooth longitudinal muscle is bluntly exposed and sharply incised close to the apex in order to achieve maximal length of the lissosphincter; the underlying mucosa is incised caudally to the colliculus. Mann-Whitney U and chi-square tests were used to compare median and proportions between the two groups, respectively. Univariate logistic regression tested the association between technique employed for apical dissection and the risk of apical PSM in overall population and in patients with apical tumor at MRI.
Results: No significantly different preoperative and pathologic characteristics were found between the two groups. Overall, 14 (7.4%) patients revealed apical PSM, including 9.9% in the control group and 5.6% in the collar group (p=0.7). Patients treated with the collar technique had significantly lower apical PSM when considering those individuals with MRI suspicious for apical tumor (0% vs 40%; p=0.001) and also those men with pT2 disease (0% vs. 8.9%; p=0.01). Continence recovery rates in collar group and control group were similar both at catheter removal and at 1, 3, 6 and 12 months (69.4% vs 76.5%, 76.9% vs 85.2%, 89.8% vs 91.4%, 97.2% vs 97.5% and 100% vs 98.8%, respectively; all p≥0.2). At univariate logistic analysis, considering patients with MRI showing an apical tumor (n= 43), the use of the collar technique was associated with a significantly lower risk of apical PSM (OR: 0.05, p=0.009).
Conclusions: The use of the collar technique allows to reduce the rate of apical PSM in case of apical tumor, preserving the length of the lissosphincter, which is essential to achieve optimal continence recovery.