Does obesity affect the outcomes of clinically localized prostate cancer in the era of extraperitoneal robot-assisted radical prostatectomy?

Purpose: Obesity has been proven to affect the outcomes in open radical prostatectomy. However, the relationship between obesity and the outcomes of robot-assisted radical prostatectomy (RARP) was not conclusive. Herein, we aimed to investigate the impact of obesity on the clinical outcomes after RARP. Materials and Methods: From April 2016 to June 2020, 164 patients underwent RARP by a single experienced surgeon at our institute. Patients with previous transurethral resection of prostate (n = 30), hernioplasty (n = 13), and transperitoneal RARP (n = 26) were excluded. Finally, 105 patients were enrolled and divided into different groups according to their body mass index (BMI) and waist circumference (WC) using the definition of Taiwan National Health Institute. BMI was categorized into three groups (normal: BMI <24, overweight: BMI between 24 and 27, and obese: BMI ≥27 [kg/m2]). WC was categorized into two groups (normal: WC <90 and central obesity: WC ≥90 [cm]). Perioperative outcomes and functional outcomes including preoperative, postoperative erectile function, and postoperative continence status were evaluated. Results: Among BMI groups, 29 patients were normal, 43 patients were overweight, and 33 patients were obese. Console time and sum time showed a significant difference in different BMI groups (P = 0.034 and 0.016, respectively). Of the 101 patients with available magnetic resonance imaging, 74 patients' WC were normal, and 27 patients were central obese. Blood loss in central obesity group was significant more than normal WC group (300 ml vs. 200 ml, P = 0.04). No significant differences were observed in pathological and functional outcomes in both groups. Conclusion: Obesity and central obesity seemed to result in longer operation time and more blood loss in extraperitoneal RARP while functional outcomes can be maintained regardless of the obesity degree. Large-scale studies are necessary to further explore the relationship between obesity and the outcomes of RARP in future.