Patients and surgical techniques

We retrospectively reviewed 257 patients with PC who underwent either RARP (n=187) or ORP (n=70) at our institution from 2011 to 2014. Since RARP started to be covered by Japanese public health insurance in 2012, most patents underwent ORP between 2011 and the first half of 2012, while majority of patients received RARP after the second half of 2012. We performed RARP using the peritoneal approach as previously described (1) and ORP using the conventional retroperitoneal approach, respectively. Patients who underwent RARP were placed in the Trendelenburg position at an angle of 2$\mathring{5}$ from the horizontal plane. Lymph node dissection was performed in RARP patients who were predicted to have ≥5% lymph node metastasis according to the Japan PC nomogram (7) and in all ORP patients. Cavernous nerve preservation was carried out on the cancer-negative lobe in RARP patients; bilateral preservation was limited only when the patient's cancer was located at the transitional zone. In ORP patients, cavernous nerve preservation was performed in a limited number of patients. All patients underwent pretreatment evaluations, including blood tests, chest x-rays, computed tomography, and bone scintigraphy. Posttreatment monitoring was generally performed with routine blood tests including prostate-specific antigen (PSA) every 1-6 months.

The present study was approved by the Internal Institutional Review Board of Graduate School of Medicine and Faculty of Medicine, University of Tokyo (approval no. 3124). Written informed consent was obtained from each patient prior to surgery. Patients were given the opportunity to decline participation in the study through the opt-out form on our website.