Pelvic lymph node dissection for prostate cancer: frequency and distribution of nodal metastases in a contemporary radical prostatectomy series.

Purpose: We determined the frequency and distribution of metastases to pelvic lymph nodes in a contemporary American radical prostatectomy series.

Materials And Methods: In 642 consecutive patients with clinically localized prostate cancer treated by a single surgeon between 2002 and 2009 pelvic lymph nodes were removed and submitted to the pathologist in separate packets (external iliac, obturator and hypogastric). We assessed the total number of nodes and the number with metastases in each packet.

Results: Complete pathological information was available for 427 patients, who had a median of 16 lymph nodes removed. Of the patients 35 (8.2%) had lymph node metastases, including 1.7% with low, 8.6% with intermediate and 23.9% with high risk cancer. Of those with nodal metastases 24 (69%) had positive lymph nodes in only 1 of the 3 areas, including the external iliac in 4 (11%), the obturator in 9 (26%) and the hypogastric in 11 (31%). Only 37% of the patients had positive nodes only in the external iliac area above the obturator nerve while 60% and 49% had at least 1 positive node in the obturator and the hypogastric area, respectively. Of the patients 80% had only 1 (49%) or 2 (31%) positive nodes.

Conclusions: In contemporary American patients with clinically localized prostate cancer lymph node metastases were found more often and frequently exclusively in the obturator and hypogastric areas than in the external iliac area. Pelvic lymph node dissection limited to the external iliac area above the obturator nerve would identify and remove lymph node metastases in only a third of the patients with positive nodes found at full pelvic lymph node dissection.