Influence of body mass index on histopathological and intraoperative criteria in a consecutive series of patients after robotic-assisted radical prostatectomy

Abstract

In various studies it has been shown that obesity enhances the risk for a unfavorable pathological tumour stages, higher Gleason scores (GS), positive surgical margins (PSM), and certain perioperative parameters (higher blood loss, higher length of surgery, higher complication rates) after radical prostatectomy. However, for robot-assisted radical prostatectomy (RARP) there are only a few studies addressing this topic with partially conflicting results. Furthermore, none of these studies actually represents the clinical practice pattern as performed in a European centre. Beside further clinical and histopathological parameters, also body mass index (BMI) of patients undergoing RARP was recorded. The following categories were registered: BMI of < 25 kg/m², ≥ 25-29.9 kg/m², and ≥ 30 kg/m² defined as normal weight, overweight, and obesity, respectively. The potential correlation between BMI on the one hand and various criteria of aggressive tumour biology and specific perioperative parameters on the other hand has been examined on univariate and multivariable analyses. 22.8% (n=79), 59% (n=204), and 18.2% (n=63) of patients of the study group presented with normal weight, overweight, and obesity, respectively. Based on the results of various multivariable regression models there was no significant influence of obesity on pathological tumour stage, pN category, undifferentiated tumour growth (≥ GS7b), upgrading, or PSM rates. Furthermore, obese patients showed a significantly higher intraoperative blood loss and a higher length of surgery, which, however, did not result in a higher rate of grade 3a/b complications according to Clavien-Dindo classification after 90 days. In the present series of consecutive patients undergoing RARP there was no evidence for a more aggressive tumour biology or a higher complication rate in obese patients.