Endophytic lesions: A predictor of failure in laparoscopic renal cryoablation

Background and Purpose: Laparoscopic renal cryoablation is an emerging minimally invasive management option for T₁ renal lesions. In an analysis of patients treated with laparoscopic cryoablation for renal lesions, our objective was to compare the treatment outcomes in patients with exophytic/partially exophytic and endophytic (peripheral but completely intrarenal) lesions. Patients and Methods: We retrospectively reviewed medical records of 32 consecutive patients with anterior renal lesions who were treated with laparoscopic renal cryoablation between 2003 and 2005. Biopsy samples were obtained from the majority of lesions intraoperatively. The lesions were managed with 17 gauge needles and two freeze/thaw cycles. Follow-up was performed with CT scans at 3, 6, and 12 months, and then yearly. Treatment failures were defined as continued enhancement on CT or growth of the lesion. Statistical analysis was performed using t-test, correlative, and multiple regression analysis. Results: A total of 35 lesions in 32 patients were identified. Median lesion size was 1.9 cm. Median age was 67 years, with most patients having significant comorbidities. The median preoperative and postoperative creatinine level was 1.3 and 1.5 mg/dL (P = 0.38). Of the biopsy samples from 27 of 35 lesions, 18 showed renal cell carcinoma, 5 were found to be benign, and findings from 4 were inconclusive. Three lesions were completely endophytic. The median follow-up was 18 months, with treatment failures noted in 2 of 35 lesions (6%), both of which were endophytic (P < 0.0001). Multivariate analysis revealed that only the endophytic status of a lesion was a predictor of failure (P < 0.05). These were lesions that relied entirely on intraoperative ultrasonography for targeting, which suggests that failure was a technical error. Conclusions: Experience with renal cryoablation is still evolving. Our series further defines the role of laparoscopic renal cryoablation and its limitations in managing peripheral endophytic tumors. Completely endophytic lesions have a significantly higher risk of treatment failure. Reliance solely on intraoperative ultrasonography with no visual cues is a risk factor for treatment failure.