The role of chitosan membranes application on the neurovascular bundles during robot-assisted radical prostatectomy: Preliminary results of a phase II study

INTRODUCTION & OBJECTIVES: Erectile dysfunction and urinary incontinence are the main postoperative sequelae in patients undergoing radical prostatectomy. The introduction of robotics in surgery for prostate cancer has helped the improvement of the oncological and functional results with more precise nerve-sparing tecnique. In parallel to this, in recent years, studies in bio-medical field proposed the application of bio-materials aimed to support nerves regeneration. The aim of the study was to evaluate the eventual improvement of functional results after nerve-sparing robot-assisted radical prostatectomy (RARP) after the application of chitosan membranes on the neurovascular bundles. MATERIAL & METHODS: From July 2015 to June 2016 98 patients who underwent nerve-sparing RARP with a pre-operative IIEF> 20 were enrolled; the chitosan membrane (CM) was applied intraoperatively. Preoperative, intraoperative, postoperative, pathological and functional variables and oncological results were analyzed. Patients were defined as continent if 0 pad or 1 Safety pad was used; they were defined as potent with a score > 2 to Question 2 of the EPIC-Sexual Assessment Questionnaire (valid erections for intercourse or masturbation). The functional results were evaluated at 1 ,2 and 3 months after catheter removal. Specifically for the purpose of the study, a cohort of consecutive patients to whom CM was not applied was matched-paired after propensity score analysis to be the control group (nCM). RESULTS: The protocol did not result in an increase in operative time, intraoperative blood loss, rate of peri- and postoperative complications and worsening of the oncological results. Nerve sparing technique was bilateral interfascial in 58, interfascial/intrafascial unilateral in 24 and in bilateral intrafascial in 16 patients. In the CM group 36 (36.34%), 47 (47.93%) and 54 (54.08%) patients were potent at 1, 2 and 3 months after surgery, respectively. In the nCM group potent patients were found to be 31 (31,63%), 41 (41.81%) and 45 (45.91%), respectively (p-value: ns). Considering only patients who could benefit from a complete preservation of neurovascular bundles (intrafascial bilateral nerve-sparing), 7 (43.75%), 11 (68.75%) and 12 (75.00%) had an early recovery of potency in the CM group at 1, 2 and 3 months after surgery, respectively; in the nCM group 6 (37,50%), 9 (56.25%) and 10 (62.50%) achieved a recovery of potency (p-value:ns). Concerning the recovery of urinary continence, no differences were found. CONCLUSIONS: The application of chitosan membranes on the neurovascular bundles during RARP is safe and feasible. Functional results showed a trend towards a faster recovery of sexual potency in patients who received CM, without substantial differences in the recovery of continence. Larger sample size are needed to eventually found a statistically significant difference in potency recovery rate derived from chitosan application.