Cryoablation of renal tumors: long-term follow-up from a multicenter experience

Abstract

Purpose: To retrospectively investigate long-term outcomes of renal cryoablation from a multicenter database.

Methods: 338 patients with 363 renal tumors underwent cryoablation in 4 centers in North-Eastern Italy. 340/363 tumors (93.7%) were percutaneously treated with CT guidance. 234 (68.8%) were treated after conscious sedation, 76 (22.3%) under local lidocaine anesthesia only and 30 (8.8%) under general anesthesia. Treatment efficacy and complication rate considered all procedures. Oncologic outcomes considered a subset of 159 patients with 159 biopsy proven renal cell carcinoma.

Results: Mean tumor size was 2.53 cm. Technical success was achieved in 355/363 (97.8%) treatments. Treatment efficacy after the first treatment was achieved in 348/363 (95.9%) tumors. Statistical analysis revealed a significant lower treatment efficacy for ASA score >3, Padua score >8, tumor size >2.5 cm, use of >2 cryoprobes, presence of one single kidney. In the subset of 159 patients, recurrence-free survival rates were 90.5% (95% CI 83.0%, 94.9%) at 3 years and 82.4% (95% CI 72.0%, 89.4%) at 5 years; overall survival rates were 96.0% (95% CI 90.6%, 98.3%) at 3 years and 91.0% (95% CI 81.7%, 95.7%) at 5 years; no patient in this subset developed metastatic disease. Clavien-Dindo >1 complications were recorded in 14/369 procedures (3.8%) and were related to age >70 years, tumor size >4 cm and use of >2 cryoprobes.

Conclusion: Cryoablation performed across four different centers in a large cohort of predominantly small renal tumors showed that this technique provides good recurrence-free survival rates and overall survival rates at three- and five-year with very low major complications rate.

Keywords: Ablation techniques; Cryoablation; Kidney neoplasm; Multicenter study.

Fig. 1

Patient selection flowchart. (RCC: Renal Cell Carcinoma; FU: Follow-Up)

Fig. 2

Incomplete tumor cryoablation. a Before cryoablation CEUS shows a homogeneously vascularized renal tumor (curved arrows). b A crescent enhancing area consistent with residual tumor (arrowheads) is present one month after the treatment of the lesion (curved arrows). c Gadolinium-enhanced subtracted image six months after the treatment shows enhancing tumor tissue (arrowhead) and confirms incomplete ablation of the lesion (curved arrows)

Fig. 3

Normal CE MR imaging appearance following cryoablation of a RCC. a Pre-ablation fat-suppressed T1-weighted CE MRI shows a 2.5 cm enhancing mass in the mid portion of the right kidney, located anteriorly (arrow). b–g Follow-up CE MRI 6 months, 1 year, 2 years, 3 years, 4 years and 5 years after cryoablation show lack of enhancement within the ablation zone together with progressive shrinkage of this area (arrows)

Fig. 4

Tumor recurrence after cryoablation of a RCC. a Pre-ablation fat-suppressed T1-weighted CE MRI shows a 3.0 cm enhancing mass in the mid portion of the right kidney, posterior to the renal vein (arrow). b, c Follow-up CE MRI 6 months and 1 year after cryoablation show lack of enhancement within the ablation zone (arrows). d Follow-up CE MRI 2 years after cryoablation. In the ablated area (arrow) there is lack of enhancement medially and new enhancement in the lateral aspect consistent with tumor recurrence

Fig. 5

Kaplan–Meier curve of recurrence-free survival (RFS) in 159 patients with 159 biopsy-proven renal cell carcinomas. Dashed lines = 95% confidence intervals. Tick marks = censored data. Estimated RFS rates: 3 years: 90.5% (83.0%–94.9%). 5 years: 82.4% (72.0%–89.4%)

Fig. 6

Kaplan–Meier curve of overall survival (OS) in 159 patients with 159 biopsy proven renal cell carcinomas. Dashed lines = 95% confidence intervals. Tick marks = censored data. Estimated OS rates: 3 years: 96.0% (90.6%–98.3%). 5 years: 91.0% (81.7%–95.7%)

Fig. 7

Hemorrhage after cryoablation of a RCC. a Pre-ablation CE CT shows a 3.5 cm enhancing mass at the lower pole of the left kidney (arrow). b CE CT obtained 1 day after cryoablation shows a perirenal hematoma (*) adjacent to the ablated area together with a pararenal hematoma (**). The patient recovered following transfusion