Decreasing rate and extent of lymph node staging in patients undergoing radical prostatectomy may undermine the rate of diagnosis of lymph node metastases in prostate cancer

Abstract

Background: At radical prostatectomy (RP), pelvic lymph node dissection (PLND) represents the most accurate staging procedure for the presence of lymph node (LN) metastases.

Objective: We evaluated the rate of PLND use and its lymph node count (LNC) over the last two decades. We also tested the relationship between LNC and the rate of pN1 stage.

Design, setting, and participants: Between 1988 and 2006, 130,080 RPs were recorded in 17 Surveillance Epidemiology and End Results registries.

Measurements: The statistical significance of temporal trends was evaluated with the chi-square trend test. Separate univariable and multivariable regression analyses tested the relationship between predictors and two end points: (1) lack of LN staging (pNx) and (2) presence of LN metastases (pN1).

Results and limitations: Stage pNx was recorded in 25.9% of patients, and pNx rate was higher in more contemporary years (30.1% in 2000-2006 vs 20.8% in 1988-1993; multivariable p < 0.001). When PLND was performed, an average of 7.4 LNs (median: 6) were removed. The average LNC decreased from 12.0 nodes (median: 12) in 1988 to 6.0 nodes (median: 4) in 2006. Overall pN1 rate was 3.4% and decreased from 10.7% to 3.1% between 1988 and 2006 (p < 0.001). LNC was an independent predictor of pN1 stage (multivariable p < 0.001).

Conclusions: An increasingly larger proportion of prostate cancer patients remain without LN staging at RP. Fewer LNs were removed at PLND over time, resulting in fewer patients diagnosed with pN1 stage at RP. The impact of this phenomenon on cancer control outcomes is still to be verified.