US-guided Percutaneous Microwave Ablation versus Open Radical Nephrectomy for Small Renal Cell Carcinoma: Intermediate-term Results

Purpose To review intermediate-term clinical outcomes of microwave ablation (MWA) compared with open radial nephrectomy (ORN) in small renal cell carcinoma (RCC) patients and to identify prognostic factors associated with two techniques. Materials and Methods This retrospective study was institutional review board–approved. A total of 163 patients (127 men and 36 women) with small RCC (≤4 cm) were included from April 2006 to March 2012. Sixty-five patients underwent MWA and 98 patients underwent ORN. Survival, recurrence, and renal function changes were compared between the two groups. Effect of changes in key parameters (ie, overall survival, RCC-related survival, and metastasis-free survival) was statistically analyzed with the log-rank test. Results Although overall survival after MWA was lower than that after ORN (P = .002), RCC-related survival was comparable to ORN (P = .78). Estimated 5-year overall survival rates were 67.3% after MWA and 97.8% after ORN; for RCC-related survival, estimated 5-year rates were 97.1% after MWA and 97.8% after ORN. There was one local tumor recurrence 32 months after MWA and none after ORN. Major complication rates were comparable (P = .81) between the two techniques (MWA, 2.5% vs ORN, 3.1%). The MWA group had less surgical time (P < .001), estimated blood loss (P < .001), and postoperative hospitalization (P < .001). Multivariate analysis showed age (P = .014), tumor type (P = .003), postoperative urea nitrogen (P = .042), comorbid disease (P = .005), and treatment modality (P < .001) may become survival rate predictors. Conclusion In intermediate term, ultrasonographically guided percutaneous MWA and ORN provide comparable results in oncologic outcomes. MWA appears to be a safe and effective technique for management of small RCC in patients with little loss of renal function. © RSNA, 2013