Purpose: The current tumor classification for renal cell carcinoma classifies pT2 tumors as larger than 7 cm in greatest dimension and limited to the kidney. We examined the current pT2 tumor classification of renal cell carcinoma and determined whether a tumor size cutoff exists that would improve prognostic accuracy.
Materials and methods: We studied 706 patients with pT2 renal cell carcinoma treated with surgical extirpation at 9 international academic centers. Data collected from each patient included age at diagnosis, gender, 2002 TNM (tumor, node, metastasis) stage, tumor size, nuclear grade, performance status, histological subtype and disease specific survival. Disease specific survival was evaluated with univariate and multivariate analysis.
Results: Median followup was 52 months. Univariate Cox regression analysis showed a significant association of tumor size with disease specific survival (HR 1.11, p<0.001). An ideal tumor size cutoff of 11 cm was identified, which led to the stratification of 2 groups with respect to disease specific survival (p<0.0001) with 5 and 10-year survival rates of 73% and 65% for pT2 11 cm or less, and 57% and 49% for pT2 larger than 11 cm, respectively. The incidence of metastases was significantly greater in the larger than 11 cm group, while Eastern Cooperative Oncology Group performance status, Fuhrman grade and histological subtype were similar. Multivariate Cox regression analysis retained tumor size as an independent prognostic factor and as the strongest prognostic factor for patients with pT2N0M0 disease.
Conclusions: Our data suggest that the current pT2 classification can be improved by subclassification into pT2a and pT2b based on a tumor size cutoff of 11 cm. Patients in the proposed pT2bN0M0 group are at higher risk for death from renal cell carcinoma and should be considered for adjuvant therapies. External validation is warranted before suggesting change to the TNM classification.