Redefining pT3 renal cell carcinoma in the modern era: A proposal for a revision of the current TNM primary tumor classification system

BACKGROUND. The 2002 American Joint Committee on Cancer (AJCC) tumor classification for renal cell carcinoma (RCC) does not take into account concomitant venous invasion and extrarenal tumor extension (ERE). In the current study, the authors evaluated the prognostic significance of venous tumor thrombus (VTT) and its extent, the presence and location of ERE, and a combination of both features on survival after the surgical management of patients with pathologic T3 (pT3) RCC. METHODS. With Institutional Review Board approval, the institutional nephrectomy database of 3470 patients treated at the University of Texas M. D. Anderson Cancer Center from 1990 to 2006 was searched for pT3 RCC patients who were treated with partial or radical nephrectomy. Patients with nonmetastatic, lymph node-negative RCC and a minimum follow-up of 6 months were included in the analysis. RESULTS. A total of 419 patients with pT3N0/NxM0 RCC and a mean follow-up of 40.8 months met the study inclusion criteria. In multivariate Cox regression analyses, the 2002 AJCC primary tumor classification was not found to be an independent predictor of cancer-specific mortality. A total of 211 patients with ERE only (50.4%) and 72 patients with VTT only (17.2%) were found to have a similar risk of death from RCC (hazards ratio [HR] of 1.018; P = .957), whereas 136 patients harboring both features (32.5%) were found to be significantly more likely to die from RCC (HR of 2.660; P < .001). The authors proposed a new primary tumor classification in which they grouped patients with both ERE and VTT (which was found to be an independent predictor of cancer-specific survival) into a separate staging category, and demonstrated improved prognostic ability when compared with the 2002 AJCC classification (c indexes of 0.625 vs 0.580, respectively). CONCLUSIONS. The prognostic accuracy of the 2002 AJCC pT3 tumor classification can be improved by subclassifying patients with ERE only and those with VTT only into a prognostic category that is separate from patients with both ERE and VTT.