Three-dimensional tumour volume and cancer-specific survival for patients undergoing nephrectomy to treat pT1 clear-cell renal cell carcinoma

OBJECTIVE To address whether information on three-dimensional tumour volume can provide additional prognostic information for patients with small, localized renal cell carcinoma (RCC) superior to tumour size alone. PATIENTS AND METHODS We identified 955 patients treated with radical nephrectomy or nephron-sparing surgery for unilateral, sporadic, pT1, pN0/NX, M0, non-cystic clear-cell RCC (ccRCC) between 1980 and 2004, including 515 pT1a patients and 440 pT1b patients. We estimated tumour volume using three tumour dimensions recorded on pathological analysis and the equation for the volume of an ellipsoid [pi/6 (length x width x height)]. For tumour size alone, we used the maximum tumour diameter recorded on pathological analysis. Univariate and multivariable associations with RCC-specific death were evaluated using Cox proportional hazards regression models summarized with hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS Among pT1a patients, the risk of RCC death associated with having a tumour volume above the median (HR = 4.55; 95% CI, 1.30-15.83; P = 0.018) was markedly higher than having a tumour size above the median (HR = 2.55; 95% CI 0.83-7.85; P = 0.10). Comparison of concordance (c) index values further supported the idea that additional prognostic information was provided by tumour volume (c = 0.659) compared with tumour size (c = 0.600) for pT1a patients. Among pT1b patients, we noted that associations of tumour volume and tumour size with RCC-specific death were similar. Multivariable adjustment did not alter our findings. CONCLUSIONS Tumour volume could provide valuable prognostic information for patients with pT1a ccRCC but not pT1b ccRCC. Future investigations are needed to confirm this finding, explore other RCC subtypes and evaluate accuracy of tumour volume determination on radiographic imaging for potential patient management before surgery.