Adequate lymphadenectomy is critical to the evaluation and staging of patients with many types of malignancies, including prostate cancer.
This article discusses the current data concerning indications for lymphadenectomy in men with prostate cancer, the appropriate number of nodes to retrieve, and the optimal extent of dissection. We also examine the questions of whether extended node dissection provides therapeutic benefit and whether node dissection is equivalent for traditional open prostatectomy and robot-assisted prostatectomy.
Most series advocate omitting lymphadenectomy in patients who are low risk (ie, PSA ≤10.0 ng/mL, who have a Gleason score ≤6, and who have clinical stage cT1c and T2a disease. It is important to remember, however, that even patients who are low risk by this definition may carry up to a 3% chance of harboring positive lymph nodes.
How many nodes are enough?
Using data from a large community-based cohort of patients in the United States, Kawakami et al found that the mean number of nodes retrieved during limited template lymphadenectomy is 5.7 (J Urol 2006; 176:1382-6). In contrast, on the basis of cadaver studies, Weingartner et al determined that the minimum acceptable number of nodes for a complete pelvic lymphadenectomy is 20 (J Urol 2001; 166:2295-6). Reasons for the disparity in number of nodes retrieved include differences in the extent of the template and differences in specimen processing. For example, Wawroschek et al found that sending lymph node packets by region, rather than en bloc, significantly increased the number of nodes identified (Eur Urol 2003; 43:132-6). Differences in pathologic examination and identification of nodes may also explain some of the variability in number of nodes reported (J Urol 2006; 176:1382-6).