Purpose: A systematic review was undertaken to provide a meta-analysis of clinical trials comparing thermal ablation with surgical nephrectomy for small renal tumours.
Methods: PubMed (MEDLINE), EMBASE, AMED, and Scopus were searched in August 2013 for eligible prospective or retrospective comparative trials following the PRISMA selection process. Thermal ablation was compared with surgical nephrectomy. Quality of included studies was assessed on the Newcastle-Ottawa Scale (NOS). The primary endpoint was disease-free survival and was analyzed on the log-hazard scale. Secondary outcome measures included complications, local recurrence, and decline of renal function. Hazard ratios (HR) and risk ratios (RR) were calculated with a random effects model, and meta-regression analysis was performed to explore clinical heterogeneity.
Results: Six clinical trials (1 randomized and 5 cohort; 6-8 stars on the NOS scale) involving 587 patients with small renal tumors (mean size 2.5 cm) treated with either thermal ablation (percutaneous or laparoscopic application of radiofrequency or microwave) or surgical nephrectomy (open or laparoscopic) were analyzed. Overall complication rate was significantly lower in the ablation group (7.4 vs. 11%; RR: 0.55, 95% confidence interval [CI]: 0.31-0.97, p = 0.04). Postoperative decline of eGFR was higher in case of nephrectomy (mean difference: -14.6 ml/min/1.73 m(2), 95% CI: -27.96 to -1.23, p = 0.03). Local recurrence rate was the same in both groups (3.6 vs. 3.6%; RR: 0.92, 95% CI: 0.4-2.14, p = 0.79) and disease-free survival also was similar up to 5 years (HR: 1.04, 95% CI: 0.48-2.24, p = 0.92).
Conclusions: Thermal ablation of small renal masses produces oncologic outcomes similar to surgical nephrectomy and is associated with significantly lower overall complication rates and a significantly less decline of renal function. More randomized, controlled trials are necessary.