Do robotic prostatectomy positive surgical margins occur in the same location as extraprostatic extension?

Purpose: Positive surgical margins (PSMs) may reflect incomplete surgical resection, while extraprostatic extension (EPE) could suggest that complete tumor resection is more difficult. This study evaluated cases with both EPE and PSMs in robotic-assisted radical prostatectomy (RARP) specimens to determine the respective locations of each.

Methods: A single institutional retrospective review of RARP performed between 2007 and 2009 was conducted to identify cases with both EPE and PSM. Prostates were entirely submitted and processed in whole mount format. All locations of EPE and PSM were recorded as was the size of the largest focus of EPE and PSM.

Results: About 8.5 % (112/1,315) of RARP had both EPE and PSM. Analysis of cases with concurrent EPE and PSM revealed that EPE occurred most commonly in the mid-gland, particularly in the posterolateral mid-prostate. In contrast, PSM was most frequent at the base (bladder neck), specifically the anterior base. 51.8 % of the cases had EPE and PSM in discordant locations, 19.6 % had EPE and PSM in the same location, and 28.6 % had areas of EPE and PSM both in the same location as well as in different locations. Cases with both concordant and discordant locations of EPE and PSM had significantly more high-risk features including higher tumor volume, more frequent positive nodes, and more frequent Gleason score ≥ 8 compared to concordant or discordant subgroups.

Conclusion: PSMs frequently did not occur in the same location as EPE. A better understanding of where EPE and PSMs occur may help guide surgical technique to decrease residual tumor.