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Comparison of the 2002 and 2010 version of the TNM classification system regarding the prediction of metastasis-free survival in patients with renal cell carcinoma.

448 Background: A new version of the TNM classification system for renal cell carcinoma (RCC) has been introduced in 2010 by the American Joint Committee on Cancer (AJCC). However, data for it's ability to predict metastasis-free survival in RCC patients from validation studies of independent cohorts are sparse. Therefore, we decided to compare the predictive ability of the 2010 vs. the 2002 version of the TNM classification system.


METHODS
Pathological reports of 2595 patients with uni- or bilateral synchronous non-metastatic (pT1-4N0M0) RCCs, treated with radical nephrectomy or nephron sparing surgery between 1984 and 2010 at a single tertiary academic center, were re-evaluated. Metastasis-free survival (MFS) was assessed using the Kaplan-Meier method and pairwise log-rank tests.


RESULTS
Mean follow up was 95 (0-322) months and 430 (16.6%) patients were found to develop metastatic disease from RCC. Pairwise comparisons revealed statistically significant differences in MFS between adjacent 2002 primary tumor classifications, including pT1a vs. pT1b (p<0.001), pT1b vs. pT2 (p=0.029), pT3a vs. pT3b (p<0.001), and pT3c vs. pT4 (p=0.007) but excluding, pT2 vs. pT3a (p=0.963) and pT3b vs. pT3c (p=0.968). With the changes to the 2010 primary tumor classification different trends in statistical significance were observed in pairwise comparisons, including pT1a vs. pT1b (p<0.001), pT3a vs. pT3b (p=0.001) but excluding pT1b vs. pT2a (p=0.062), pT2a vs. pT2b (p=0.856), pT2b vs. pT3a (p=0.395), pT3b vs. pT3c (p=0.891) and pT3c vs. pT4 (p=0.933).


CONCLUSIONS
The 2010 version of the TNM classification system remains a robust predictor of MFS compared to the 2002 version. However, the 2010 version showed less discriminative power in higher pT-stages compared to the 2002 version of the TNM classification system.