Impact of obesity on clinicopathologic outcomes after robot-assisted laparoscopic prostatectomy

Purpose: To investigate the impact of body mass index (BMI) on pathologic and functional outcomes after robot-assisted laparoscopic prostatectomy (RALP). Patients and Methods: We evaluated 400 consecutive patients who underwent RALP at the Mayo Clinic between 2002 and 2006. Patients were categorized as normal weight (BMI <25 kg/ m², n = 94), overweight (BMI 25-29.9 kg/m ², n = 187), and obese (BMI ≥30 kg/m², n = 119). Clinicopathologic features of the groups were compared, and logistical regression analysis was used to assess the associations of BMI with pathologic and functional outcomes after RALP. Results: Overweight and obese patients were more likely to have pT_3/4 disease (P = 0.0024) and pathologic Gleason 7 to 10 cancers (P < 0.0001). Overall, 9/94 (9.6%) normal-weight patients had a positive surgical margin (SM), compared with 25/187 (13.4%) overweight patients and 21/119 (17.6%) obese men (P = 0.087). On multivariate analysis, however, increasing BMI was not significantly associated with an increased risk of positive SM (odds ratio 1.12, 95% confidence interval 0.72-1.76, P = 0.61). In addition, although obese men had longer operative times (P = 0.049) and greater intraoperative blood loss (P = 0.04), we found no association between BMI and transfusion requirement (P = 0.34), length of hospital stay (P = 0.54), or the rates of early (P = 0.37) or late (P = 0.86) complications. Moreover, in those patients with follow-up available at 1 year after RALP, obesity did not impact the return of continence (P = 0.62) or potency (P = 0.13). Conclusion: BMI was not an independent predictor of positive SM, complications, incontinence, or erectile dysfunction after RALP. These data suggest that RALP may offer equivalent margin rates and functional outcomes for patients across BMI.