Laparoscopic renal cryoablation using ultrathin 17-gauge cryoprobes: mid-term oncological and functional results

Abstract

Study Type - Therapy (case series).

Level of evidence: 4. What's known on the subject? and What does the study add? Laparoscopic Cryoablation of renal masses has a low persistence and recurrence rates at short term follow-up albeit higher than Partial Nephrectomy. Long term results are scarcely reported. It is however a NSS technique suitable for high-risk that preserves renal function. The study provides (1) mid-term oncological outcomes of laparoscopic cryoablation of renal masses stratified by primary pathology (RCC, benign mass or undetermined biopsy) and (2) data on renal function evolution up to one year of follow-up supporting the fact that the only predictor of (moderate)renal insufficiency development after Laparoscopic cryoablation is the eGFR at baseline.

Objective: To present the functional and oncological mid-term results of laparoscopic cryoablation of renal masses using third generation ultrathin (17-gauge[G]) cryoprobes.

Patients and methods: • Consecutive patients with small renal masses treated by cryoablation from September 2003 to September 2008 were prospectively evaluated. The cryoablation was performed using multiple third generation 17-G cryoprobes after intraoperative mass biopsy. • Data on serum creatinine measurements and cross sectional imaging (computed tomography/magnetic resonance imaging) were regularly collected according to a previously determined protocol. Follow-up was censored in October 2009. • Renal function analysis was based on estimated glomerular filtration rate (eGFR) at 1 year compared with baseline. Residual (or persistent tumour) and recurrence were defined as the presence of residual enhancement at first follow-up and 'de novo' enhancement of a non-enhancing cryolesion at any time during follow-up. • Survival data were analysed using the Kaplan-Meier method. Best estimates for the overall survival (OS), recurrence-free survival (RFS), cancer-specific survival (CSS) and metastatic-free survival (MFS) were made for patients with renal cell carcinoma (RCC) and for patients with RCC or non-diagnostic biopsy.

Results: • A total of 92 patients (100 tumours; mean size 2.5 ± 0.8 cm) were treated in 95 sessions. The mean follow-up was 30.2 ± 16.6 months (Mean values are ±SD). • Intraoperative biopsy showed RCC in 51 patients (53.7%), benign lesion in 23 patients (24.2%) and was non-diagnostic in 21 patients (22.1%). Three tumour persistences and four radiological recurrences were detected. • The estimated mean RFS time and 3-year OS and RFS in patients with RCC exclusively were 47.8 (95% confidence interval [CI]: 44.1-51.1) months, 86.1% (95% CI: 71.2-93.6) and 91.8% (95% CI: 76.3-97.3), respectively. The figures were slightly higher in the group of patients with RCC or unknown pathology. The actual CSS and MFS rates were 100%. • Renal function was preserved in 84.5% of patients with normal preoperative eGFR. • Baseline eGFR was the only predictor of renal insufficiency development at 1-year follow-up.

Conclusion: Laparoscopic cryoablation with multiple ultrathin cryoprobes is oncologically and functionally effective at mid-term follow-up.