Comparison of different lymph node staging schemes in prostate cancer patients with lymph node metastasis

In addition to standard TNM N staging, lymph node ratio (LNR) and log odds of metastatic lymph node (LODDS) staging methods have been developed for cancer staging. We compared the prognostic performance of the total number of lymph nodes examined (TNLE), number of metastatic lymph node (NMLN), LNR, and LODDS in prostate cancer.

Data from 1400 patients diagnosed with prostate cancer between 2004 and 2009 who underwent lymphadenectomy were extracted from the Surveillance Epidemiology and End Results database. Kaplan-Meier methods and multivariable Cox regression analysis were used to evaluate the prognostic value of different lymph node staging schemes in patients with lymph node metastasis.

Univariate analysis showed that age, T stage, radiotherapy history, Gleason score, LNR classification, LODDS classification, and NMLN except TNLE classification were significant prognostic factors for overall survival. In multivariate analysis, LNR classification, LODDS classification, and NMLN but TNLE classification remained significant prognostic factors for overall survival. LNR classification had the highest C-index (0.672; 95% confidence interval [CI]: 0.609-0.734) and the lowest Akaike information criterion (AIC) (4057.018), indicating the best prognostic performance. Scatter plots showed that LODDS increased with increasing LNR, exhibiting a strong overall correlation between these two lymph node staging methods (r² = 0.9072). LNR and LODDS generally increased with increasing NMLN, although the correlation was relatively low.

Our results indicate that LNR and LODDS may be better predictors of overall survival than the AJCC/UICC N category in patients undergoing curative surgery for prostate cancer.