Kidney size and cancer-specific survival for patients undergoing nephrectomy for pT1 clear cell renal cell carcinoma.

Objective: To examine the association between kidney size and renal cell carcinoma (RCC) death among patients with Stage pT1 clear cell RCC undergoing surgery.

Methods: We used a case-cohort design and evaluated 191 patients from our Nephrectomy Registry who had undergone open radical nephrectomy for unilateral, sporadic, Stage pT1N0/NxM0, noncystic clear cell RCC from 1989 to 2004. Of these, 47 patients died of RCC ("cases") and 144 patients were alive at the last follow-up visit or had died of other causes ("cohort"). Univariate and multivariate associations with RCC death were evaluated using weighted Cox regression analysis and summarized with hazard ratios and 95% confidence intervals.

Results: The median kidney size was 12 cm. We observed a positive association between increasing kidney size and the risk of RCC death. A 1-cm increase in kidney size was associated with an 18% increased risk of RCC death, even after adjusting for tumor size, nuclear grade, and the presence of necrosis. After multivariate adjustment, those patients with a kidney size greater than the median were 95% more likely to die of RCC than those with a kidney size less than the median (hazard ratio 1.95, 95% confidence interval 1.00-3.81; P = .05). The limitations of our study included a lack of data on the 3-dimensional kidney volume and an inability to generalize to patients with larger tumors (ie, Stage pT2) or other RCC subtypes.

Conclusion: Our data suggest that kidney size is an independent predictor of survival for patients with Stage pT1 clear cell RCC. Future investigations are needed to confirm this finding and investigate this issue in larger, organ-confined tumors and other RCC subtypes.