To compare changes in renal function after radical nephrectomy for renal cell carcinoma (RCC) and radical nephroureterectomy for upper tract urothelial carcinoma (UTUC), and assess their effects on non–cancer-specific mortality (CSM).

Clinicopathologic data from 1114 patients with RCC or UTUC treated surgically from 1997 to 2013 were compiled. Patients who underwent nephron-sparing surgeries, had bilateral disease, received chemotherapy, or had <1 month of follow-up were excluded. Renal function (estimated glomerular filtration rate [eGFR]) was calculated preoperatively, 3 months postoperatively, and at last follow-up. Events were defined as ≥25% decline in eGFR from baseline. Event-free survival and non-CSM were assessed using Kaplan-Meier analysis. Multivariable Cox regression was performed to identify predictors of events.

Four hundred thirty-five patients were included (317 radical nephrectomy, 118 radical nephroureterectomy). Median follow-up was 38.2 months. UTUC patients were older (P < .001), had worse Charlson score (P < .001), and more frequently used tobacco (P = .006). Median baseline eGFR was lower in UTUC patients (58.4 vs 74.9, P < .001). RCC patients experienced a larger event rate following surgery at first (56.8% vs 31.4%, P < .001) and last (51.7% vs 35.6%, P = .003) follow-up than UTUC patients. On Kaplan-Meier analysis, UTUC patients exhibited worse non-CSM (P < .001). Postsurgical decline in renal function was a significant predictor of non-CSM in RCC patients at first (hazard ratio = 4.71, P = .041) and last (hazard ratio = 4.56, P = .018) follow-up, whereas this was not the case for UTUC patients.

UTUC patients had worse baseline eGFR and overall health status than RCC patients. RCC patients experienced greater postsurgical declines in renal function. These results shed light on differences in patient characteristics between these forms of kidney cancer and guide expectations for postoperative renal function.