Impact of Median Lobe Anatomy: Does Its Presence Affect Surgical Margin Rates During Robot-Assisted Laparoscopic Prostatectomy?

Abstract

To measure and describe the impact of median lobe anatomy on surgical margin status after robot-assisted laparoscopic prostatectomy (RALP). We prospectively collected median lobe status, surgical margin status, and other perioperative data on 791 patients who underwent RALP at our institution by 12 surgeons between August 2008 and December 2010. We performed univariable and multivariable analysis to measure the association between median lobe status and positive surgical margin rates, including site. Compared with patients without a median lobe (n=672), patients with a median lobe (n=119) were less likely to have a positive surgical margin (16% vs 24.4%). They had a higher prostate-specific antigen (PSA) level (6.1 ng/dL vs 5.4 ng/dL), lower Gleason scores (<7, 58.1% vs 42.1%), lower pathologic stages (T(2), 87.4% vs 75.4%), and larger prostates (64 g vs 48 g) (all P<0.05). In our multivariable model, the effect of median lobe anatomy on surgical margin status, after adjusting for these factors, was not statistically significant (relative risk 0.97, 95% confidence interval, 0.64-1.47, P=0.88). Lower PSA level, Gleason score, and pathologic stage and larger prostates, however, predicted decreased positive surgical margin rates (P<0.01). Although presence of median lobe anatomy is not an independent predictor of positive surgical margins in RALP, it is associated with favorable pathologic characteristics that are known to predict decreased positive surgical margins.