Preserving Renal Function through Partial Nephrectomy Depends on Tumor Complexity in T1b Renal Tumors

This study aimed to determine patients with T1b renal cell carcinoma (RCC) who could benefit from partial nephrectomy (PN) and method to identify them preoperatively using nephrometry score (NS). From a total of 483 radical nephrectomy (RN)-treated patients and 40 PN-treated patients who received treatment for T1b RCC between 1995 and 2010, 120 patients identified through 1:2 propensity-score matching were included for analysis. Probability of chronic kidney disease (CKD) until postoperative 5-years was calculated and regressed with respect to the surgical method and NS. Median follow-up was 106 months. CKD-probability at 5-years was 40.7% and 13.5% after radical and PN, respectively (P = 0.005). While PN was associated with lower risk of CKD regardless of age, comorbidity, preoperative estimated renal function, the effect was observed only among patients with NS ≤ 8 (P < 0.001) but not in patients with NS ≥ 9 (P = 0.746). Percent operated-kidney volume reduction and ischemia time were similar between the patients with NS ≥ 9 and ≤ 8. In the stratified Cox regression accounting for the interaction observed between the surgical method and the NS, PN reduced CKD-risk only in patients with NS ≤ 8 (hazard ratio [HR], 0.054; P = 0.005) but not in ≥ 9 (HR, 0.996; P = 0.994). In T1b RCC with NS ≥ 9, the risk of postoperative CKD was not reduced following PN compared to RN. Considering the potential complications of PN, minimally invasive RN could be considered with priority in this subgroup of patients.