Prognostic stratification of localized renal cell carcinoma by tumor size

Recent retrospective studies have challenged the current TNM classification of 7.0 cm to distinguish between T1 and T2 tumors. We reevaluated the optimal tumor size cutoff point that independently differentiates patient prognosis beyond the other accepted prognostic features.

From 1990 to October 2006, 398 patients who underwent radical nephrectomy for localized renal cell carcinoma (T1-T2, N0, M0) were followed prospectively. Median followup was 5.3 years and 37 patients died of tumor related causes. The optimal tumor cutoff point was calculated and multivariate Cox proportional hazards models were used to adjust for the effects of Fuhrman grade, tumor type, sex, age and Karnofsky performance status on cancer specific survival. Sensitivity analysis included all 66 patients with elective nephron sparing surgery.

Univariate analysis supported 7 cm as the optimal cutoff point for prognostic stratification (p = 0.002). The 4 cm cutoff point that is used to distinguish between stage T1a and T1b could not be confirmed with analogous statistical significance (p = 0.20). On multivariate analysis tumor size dichotomized at 7 cm was an independent prognostic factor (HR 2.89, 95% CI 1.46-5.73, p = 0.002), as was Fuhrman grade 3 (HR 3.68, 95% CI 1.37-9.83, p = 0.010) and age older than 60 years (HR 3.64, 95% CI 1.63-8.14, p = 0.002). The inclusion of patients with elective nephron sparing surgery confirmed these results.

Univariate and multivariate analyses of our patient cohort undergoing radical nephrectomy for localized renal cell carcinoma showed no cutoff point other than 7 cm to be more suitable for distinguishing between T1 and T2 tumors, supporting the current TNM classification. In T1 tumors the analysis did not allow a clear dichotomization of tumor size in this group.