Extended lymph node dissection in robot-assisted radical prostatectomy: lymph node yield and distribution of metastases.

In this study, we reported our experience performing robotic extended lymph node dissection (eLND) in patients with prostate cancer. A total of 147 patients with intermediate and high-risk prostate cancer who underwent robotic eLND from May 2008 to December 2011 were included in this analysis. The dissection template extended to the ureter crossing the iliac vessels. We assessed lymph node yield, lymph node positivity, and perioperative outcomes. Lymph node positivity was also evaluated according to the number of lymph nodes (LNs) removed (<22 vs ≥22). The median number of LNs removed was 22 (11-51), and 97 positive LNs were found in 24 patients (16.3%). While the obturator fossa was the most common site for LN metastases (42.3%, 41/97), the internal iliac area was the most common area for a single positive LN packet (20.8%, 5/24). Eight patients (33.3%, 8/24) had positive LNs at the common iliac area. The incidence of positive LNs did not differ according to the number of LNs removed. Complications associated with eLND occurred in 21 patients (14.3%) and symptomatic lymphocele was found in five patients (3.4%). In conclusion, robotic eLND can be performed with minimal morbidity. Furthermore, LN yield and the node positive rate achieved using this robotic technique are comparable to those of open series. In addition, the extent of dissection is more important than the absolute number of LNs removed in eLND, and the robotic technique is not a prohibitive factor for performing eLND.