A population-based assessment of the National Comprehensive Cancer Network practice guideline indications for pelvic lymph node dissection at radical prostatectomy.

OBJECTIVES: To examine the ability of the threshold recommended by the National Comprehensive Cancer Network (NCCN) in correctly predicting histologically-confirmed lymph node invasion (LNI). The 2010 NCCN practice guidelines for prostate cancer recommend a pelvic lymph node dissection (PLND) at radical prostatectomy in all individuals with a nomogram predicted LNI risk of ≥2%. PATIENTS AND METHODS: We assessed 20,877 patients who were treated with radical prostatectomy and PLND between 2004 and 2006, within the Surveillance, Epidemiology and End Results database. The 2% nomogram threshold, as well as other threshold values (range 1-10%) were tested. Finally, we externally validated the NCCN guideline nomogram.
RESULTS: Overall, 2.5% of patients had LNI. The use of the 2% threshold would allow the avoidance of 23% of PLNDs, at the cost of missing 1.7% of patients with LNI. Conversely, the use of a 3% threshold would allow the avoidance of 58% of PLNDs, at the cost of missing 15% of patients with LNI vs 72% and 26%, respectively, for the 4% threshold. Overall, the accuracy of the NCCN guideline nomogram quantified according to the receiver-operator characteristics-derived area under the curve was 82%.
CONCLUSIONS: In a population-based sample, the NCCN guideline nomogram is highly accurate. However, the 2% threshold will permit the avoidance of only 23% of PLNDs, instead of the 48% intended by the NCCN guidelines. The use of a 3% threshold may allow a lower rate of PLND overtreatment, although it will miss more patients with LNI.