Impact of obesity on perioperative, functional and oncological outcomes after robotic-assisted radical prostatectomy in a high-volume center

Objective To compare surgical, oncological and functional outcomes between obese vs. normal-weight prostate cancer (PCa) patients treated with robotic-assisted radical prostatectomy (RARP). Materials and methods We assessed 4555 consecutive RARP patients from a high-volume center 2008–2018. Analyses were restricted to normal-weight vs. obese patients (≥ 30 kg/m 2 ). Multivariable cox regression analyses (MVA) assessed the effect of obesity on biochemical recurrence (BCR), metastatic progression (MP), erectile function and urinary continence recovery. Analyses were repeated after propensity score matching. Results Before matching, higher rates of pathological Gleason Grade group ≥ 4 (14 vs. 18%; p = 0.004) and pT3 stage (33 vs. 35%; p = 0.016) were observed in obese patients, with similar observations for surgery time, blood loss and 30-day wound- and surgical complication rates. For normal-weight vs. obese patients, BCR- and MP-free rates were 86 vs. 85% ( p = 0.97) and 97.5 vs.97.8% ( p = 0.8) at 48 months. Similarly, rates of erectile function at 36 months and urinary continence at 12 months were 56 vs. 49% ( p = 0.012) and 88 vs. 85% ( p = 0.003), respectively. Before and after propensity score matching, obesity had no effect on BCR or MP, but a negative effect on erectile function (matched HR 0.87, 95%CI 0.76–0.99; p = 0.029) and urinary continence recovery (matched HR 0.91, 95%CI 0.84–0.98; p = 0.014). Conclusions Obesity did not represent a risk factor of BCR or MP after RARP despite higher rates of adverse pathological features. However, obesity was associated with higher risk of perioperative morbidity and impaired functional outcomes. Such information is integral for patient counselling. Thus, weight loss before RARP should be encouraged.