Long-term oncologic outcomes of laparoscopic renal cryoablation as primary treatment for small renal masses - Beyond the Abstract

Historically, Laparoscopic renal cryoablation [LRC] was considered as an inferior treatment option relative to PN with respect to oncologic outcomes. However, the most recent long-term assessments of cancer control showed comparable outcomes with either treatment strategies. In consequence, current guidelines admit that available evidence does not allow any definitive recommendations regarding oncological outcomes in favor of LRC or PN.

Such caution is justified by the lack of data regarding long-term oncologic outcomes of LRC as first treatment for small renal masses [SRM]. Under this light, we evaluated the long-term cancer control in patients with a single cT1a SRM without a previous history of renal cell carcinoma [RCC] treated with LRC at our center.

The study design was a retrospective analysis of 174 consecutive patients who received LRC as first treatment for a single CT or MRI contrast-enhancing cT1a SRM between 2000 and 2013. Patients with a previous history of RCC were excluded. Treatment failure was evaluated 1-day after surgery. Local recurrence, metachronous SRM, systemic progression, disease relapse, cancer specific mortality and all cause mortality were evaluated 10 years after surgery. Kaplan-Meier plots were used to depict outcome-free survival rate.

Median patient age was 66 years. Median tumor size was 20 mm. Median follow-up was 48 months. A significant decrease in the dimension of the cryo-ablated tumor was recorded over time (Figure 1). Within patients with biopsy proven RCC (63%, n=109), the treatment failure-free rate was 98%. The 10-years recurrence-free survival rate was 95% and the 10-years metachronous SRM-free survival rate was 87%. The 10-years systemic progression-free survival rate was 100% and the 10- years disease relapse-free survival rate was 81%. The cancer specific mortality-free survival rate was 100% and the all cause mortality free-survival rate was 62%.

The clinical implications of our results are several-fold. First, 10 years after LRC themajority of patients was free from disease relapse; second, it is hard to determine if the development of a metachronous SRM, which was recorded in 13% of our cohort after 10 years, should be considered a surgical failure rather than an independent event of carcinogenesis; third, LRC resulted into an optimal systemic progression-free survival and CSM-free survival rate. It is also noteworthy that in all the cases of disease relapse, secondary treatment was always applicable. Based on these observations, primary LRC deserve better consideration as a treatment option for SRM; moreover it might provide non-inferior oncologic outcomes than extirpative surgery. Unfortunately, the current report does not allow such assumption, since the lack of a control arm treated with extirpative surgery represent the main limitation of the current study.

In conclusion, our result showed that LRC provides safe long-term cancer control in patients newly diagnosed with a single cT1a SRM. Treatment failure and local recurrence are uncommon. Systemic progression-free survival and cancer specific-free survival are optimal. Such encouraging results reflect the stringent selection criteria applied to our population, since the selection of patients without a previous history of renal malignancy represents a necessary condition for the evaluation of LRC as a primary treatment for kidney cancer and for a valid comparison with other surgical therapies.

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Figure 1. Box and whisker plot depicting tumor dimension (mm) at diagnosis and cryolesion dimension at MRI follow-up
Residual cryolesion: median percentage of residual cryolesion dimension
Time: measured in months from surgery unless otherwise specified
Wilcoxon signed-rank test was use to compare the cryolesion dimension recorded 1 day after surgery with the cryolesion dimension at all the other measured time intervals

Written by:
Alessandro Larcher
Division of Oncology, Unit of Urology, URI, IRCCS Ospedale San Raffaele,
Università Vita-Salute San Raffaele, Milan, Italy

Nicola Fossati
Cancer Prognostics and Health Outcomes Unit, University of Montreal Health Center, Montreal, Canada.

Abstract: Long-term oncologic outcomes of laparoscopic renal cryoablation as primary treatment for small renal masses