Elsevier

European Urology

Volume 58, Issue 4, October 2010, Pages 588-595
European Urology

Kidney Cancer
Validation of the 2009 TNM Version in a Large Multi-Institutional Cohort of Patients Treated for Renal Cell Carcinoma: Are Further Improvements Needed?

https://doi.org/10.1016/j.eururo.2010.07.006Get rights and content

Abstract

Background

A new edition of the TNM was recently released that includes modifications for the staging system of kidney cancers. Specifically, T2 cancers were subclassified into T2a and T2b (≤10 cm vs >10 cm), tumors with renal vein involvement or perinephric fat involvement were classified as T3a cancers, and those with adrenal involvement were classified as T4 cancers.

Objective

Our aim was to validate the recently released edition of the TNM staging system for primary tumor classification in kidney cancer.

Design, setting, and participants

Our multicenter retrospective study consisted of 5339 patients treated in 16 academic Italian centers.

Intervention

Patients underwent either radical or partial nephrectomy.

Measurements

Univariable and multivariable Cox regression models addressed cancer-specific survival (CSS) after surgery.

Results and limitations

In the study, 1897 patients (35.5%) were classified as pT1a, 1453 (27%) as pT1b, 437 (8%) as pT2a, 153 (3%) as pT2b, 1059 (20%) as pT3a, 117 (2%) as pT3b, 26 (0.5%) as pT3c, and 197 (4%) as pT4. At a median follow-up of 42 mo, 786 (15%) had died of disease. In univariable analysis, patients with pT2b and pT3a tumors had similar CSS, as did patients with pT3c and pT4 tumors. Moreover, both pT3a and pT3b stages included patients with heterogeneous outcomes. In multivariable analysis, the novel classification of the primary tumor was a powerful independent predictor of CSS (p for trend <0.0001). However, the substratification of pT1 tumors did not retain an independent predictive role. The major limitations of the study are retrospective design, lack of central pathologic review, and the small number of patients included in some substages.

Conclusions

The recently released seventh edition of the primary tumor staging system for kidney tumors is a powerful predictor of CSS. However, some of the substages identified by the classification have overlapping prognoses, and other substages include patients with heterogeneous outcomes. The few modifications included in this edition may have not resolved the most critical issues in the previous version.

Introduction

TNM classification is the globally accepted method of describing the anatomic extent of cancer. In kidney tumors, the outcome stratification proposed in the sixth edition of the TNM, published in 2002, was validated in several studies [1], [2], [3]. However, some studies suggested that patients with localized cancers could be better dichotomized around a tumor diameter of 5–6 cm [4], [5], [6], [7] and that T3a and pT3b stages were heterogeneous [8]. Consequently, several proposals for further updates were implemented, both for localized [9], [10] and locally advanced [11], [12], [13], [14], [15], [16], [17] disease.

Very recently, the Union Internationale Contre le Cancer (UICC) and the American Joint Committee on Cancer (AJCC) released the seventh edition of the staging system, which took effect on January 1, 2010. In this latest update, some modifications were made to the staging system for kidney tumors. In comparison with the sixth edition of TNM, T2 cancers were subclassified into two subgroups based on a tumor size cut-off point of 10 cm (T2a ≤10 cm vs T2b >10 cm). Moreover, tumors with renal vein involvement or perinephric fat involvement were classified as T3a, whereas those with adrenal involvement were classified as T4 cancers. All the other categories were unchanged [18].

The purpose of the present study was to validate the recently released seventh edition of the TNM staging system for primary tumor classification in kidney tumors in a multicenter series of patients with renal cell carcinoma (RCC) treated with radical nephrectomy (RN) or partial nephrectomy (PN) in 16 academic centers in Italy.

Section snippets

Patients and methods

The Surveillance and Treatment Update Renal Neoplasms (SATURN) project was promoted by LUNA, the Leading Urological No-Profit Foundation for Advanced Research of the Società Italiana di Urologia (ie, the Italian Society of Urology). A total of 16 academic centers in Italy provided data. The database comprised 5893 patients who underwent RN or PN between 1995 and 2007 because of a suspicion of kidney cancer. The patients with benign histology (n = 430), those lacking histologic subtypes of the

Results

Table 1 summarizes the clinical and pathologic features of the 5339 analyzed patients. Based on the novel TNM staging system, 1897 of the patients (35.5%) were classified as pT1a, 1453 (27%) as pT1b, 437 (8%) as pT2a, 153 (3%) as pT2b, 1059 (20%) as pT3a, 117 (2%) as pT3b, 26 (0.5%) as pT3c, and 197 (4%) as pT4.

At a median follow-up of 42 mo (IQR: 24–75 mo), 3949 patients (74%) were alive and disease free, 786 (15%) had died of disease, and 335 (6%) had died of other causes. Median follow-up of

Discussion

We have reported what is to our knowledge the first attempt to validate the recently released seventh edition of the TNM staging system for RCC. In the present series, the novel classification of the primary tumor was a powerful independent predictor of CSS. However, some of the substages identified by the classification had overlapping prognoses (pT2b and pT3a; pT3c and pT4 RCC), whereas both pT3a and pT3b stages included patients with heterogeneous outcomes. Lastly, in multivariable analysis,

Conclusions

In the present series, the recently released seventh edition of the primary tumor staging system for RCC was a powerful independent predictor of CSS. However, some of the substages identified by the classification had overlapping prognoses, whereas other substages included patients with heterogeneous outcomes. Although in the past few years several reports have highlighted the need to change the TNM classification both for localized and locally advanced stages, only a few modifications have

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