Background
Laparoscopic robot-assisted radical prostatectomy (LRAP) has been performed at our institution since November 2003. Since January 2000 all open radical prostatectomy (ORP) specimens, and subsequent LRAP specimens have been evaluated prospectively using a standardized surgical pathology data template. We present a detailed evaluation and comparison of positive surgical margins (SM) in ORP and LRAP performed at our institution.
Methods
Non-randomized, prospective, single-institution comparison of positive SM in patients treated by ORP and LRAP. The side and location of positive SM were determined (apex, mid, base, anterior, bladder neck). Demographic, intra-operative, and surgical pathologic parameters were assessed. Chi square tests were used to compare qualitative variables, and two-tailed t tests on means for independent samples to compare quantitative variables.
Results
221 ORP and 90 LRAP were evaluated. The overall positive SM rate for ORP was 23.9% and LRAP was 13.3% (p=0.04). For ORP apical positive SM were most common, with left apical positive SM more common as compared to LRAP (10.9% vs 4.4%, p=0.03), as were any left-sided positive SM (16.7% vs 6.7%, p=0.02). Right sided positive SM were not significantly more common in ORP as compared to LRAP (p=0.09). For LRAP the most common positive SM was at the prostate base (5.6%). Comparing ORP to LRAP, the mean age (60.6 vs 59.6) and presenting PSA (6.99 vs 6.94) were similar, mean estimated blood loss (1016 ml vs 203 ml, p<0.0001) and transfusion rates (38.9% vs 0%, p<0.0001) were higher, and bilateral nerve-sparing procedures were lower (34.4% vs 53.4%, p=0.01). Pathologic tumor grade, stage and prostate weight were similar. However for ORP the maximal tumor diameter was greater than for LRAP (1.4 cm vs 1.19 cm, p=0.01).
Conclusions
At our institution the positive SM rate is significantly lower for LRAP as compared to ORP. Improved visualization, less blood loss, and greater technical precision may be contributing factors. Further accumulation of LRAP cases will be necessary to confirm this finding.

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