Study design

A total of 767 male cases received RARP at Fujita Health University Hospital (Toyoake, Japan) between August 2009 and December 2016. Median age was 66 years old and the range was from 45 to 88 years. Among the 767 cases screened for the present study, 230 high-risk PCa cases who were observed for >6 months comprised the study cohort for retrospective analysis. The mean age for the high-risk cohort is provided in Table I. All cases had non-metastatic and clinically high-risk PCa, as defined according to the D'Amico risk stratification system (17), and exhibited at least one of the following: i) A serum PSA level of >20 ng/ml (measured using a American Cancer Society-PSA kit (Ciba Corning Diagnostics Corp.) with chemiluminescent immunoassay, according to the manufacturer's instructions; ii) GS ≥8; or iii) clinical stage ≥T2c. TNM classification was defined using the American Joint Committee on Cancer staging manual (18). The following clinical variables were evaluated: Age, serum PSA level (ng/ml), clinical T stage, GS and neoadjuvant treatment. The criteria for NS RARP were: Bilateral NS, at least two factors (PSA <10 ng/ml, cT1c, <GS 7, <30% of positive-core ratio on the NS side); unilateral NS, <cT2b or <30% positive-core ratio on the NS side; non-NS, other than the aforementioned criteria. All patients received pelvic lymph node dissection. Surgery time, estimated blood loss (EBL), console time, pathological stage (pT stage), positive lymph node metastases [pN (+)], and surgical margin positivity were recorded to assess perioperative parameters. The schedule after RARP surgery consisted of a PSA assay every 3 months for the first 2 years, every 6 months for the following 3 years and annually thereafter. The number of pads used daily, at 3 months and 6 months after RARP, was checked to assess urinary continence recovery. The onset of BCR was defined as the date when the serum PSA level was >0.2 ng/ml. The time to events was calculated from the day of RARP.

Clinical characteristics of NS and non-NS robot-assisted radical prostatectomy cases.

The protocol of the present study was approved by the Ethics Committee of Fujita Health University Hospital (approval no. HM 18-115), and the present study was performed in accordance with the ethical standards laid down in the most recent version of the Declaration of Helsinki.