# Cryoablation of Small Renal Tumors in Patients

Authors: Ravi Munver; Grant I.S. Disick; Salvatore A. Lombardo; Vladislav G. Bargman; Ihor S. Sawczuk
Journal: Advances in Urology
 (2008)

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## Abstract

Introduction. The purpose of this study was to evaluate the role of renal cryoablation in patients with solitary kidneys with the goals of tumor destruction and maximal renal parenchymal preservation. Methods.  Eleven patients with single tumors were treated with cryoablation, of which 10 patients had solitary kidneys and 1 had a nonfunctioning contralateral kidney.  All procedures were performed via an open extraperitoneal approach; ten tumors were treated with in-situ cryoablation and 1 tumor was treated with cryo-assisted partial nephrectomy. Results.  Cryoablation was successfully performed without any preoperative complications.  Mean patient age was 62.4 years (range 49–79), tumor location included: 6 (upper pole), 2 (mid-kidney), 3 (lower pole).  The mean and median tumor size was 2.6 cm and 2.8 cm (range 1.2–4.3 cm), mean operative time 205 minutes (range 180–270 minutes), blood loss 98.5 ml (range 40–250 ml), and hospitalization 4.6 days (range 3–8 days). Creatinine values included: preoperative 1.43 mg/dL (range 1.2–1.9), postoperative 1.67 mg/dL (range 1.5–2.5), and nadir 1.57 mg/dL (range 1.3–2.1).  All patients were followed postoperatively with magnetic resonance imaging for surveillance.  At a median follow-up of 43 months, 9 patients had no evidence of recurrence, 1 patient has an enhancing indeterminate area, and 1 patient was lost to follow-up. Conclusion.  Intermediate-term results suggest that renal cryoablation offers a feasible alternative for patients that require a maximal nephron-sparing effort with preservation of renal function and minimal risk of tumor recurrence.


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## Body

## 1. Introduction

Nephron-sparing surgery (NSS)
entails complete resection or destruction of a renal tumor while maximizing
preservation of normal parenchymal tissue. Improvements in surgical techniques have gradually
led to more widespread utilization of partial nephrectomy with acceptable
postoperative morbidity and equivalent oncologic efficacy as compared to
radical nephrectomy. Cryoablation is an
alternative to partial nephrectomy for the treatment of renal tumors and it
employs the concept of nephron-sparing surgery [1, 2].The purpose of this study was to
evaluate cryoablation as an NSS technique for the treatment of small renal
masses in patients with solitary kidneys. We reviewed the application, effect on renal
function, and intermediate outcomes of cryoablation in this subset of patients that
require maximal renal parenchyma preservation while fulfilling the goal of
tumor destruction.


## 2. Materials and Methods

Between August 2000 and November
2004, 11 patients (9 male, 2 female) were treated with renal cryoablation for
suspicious renal lesions. All patients
had a single renal mass suspicious for malignancy based on radiologic imaging
studies. Ten patients had a solitary
kidney and 1 had a nonfunctioning contralateral
kidney. Cryoablation was selected in order to offer patients a nephron-sparing procedure in cases that, due to tumor location, were not ammenable to partial nephrectomy. Patients did not
receive preoperative biopsy of the renal mass lesion due to the associated risk
of bleeding and renal injury in patients with solitary kidneys. Ten tumors were
treated with insitu cryoablation and 1 tumor was treated with cryoassisted
partial nephrectomy.An extraperitoneal flank incision
was made between the 10th and 11th ribs allowing exposure of the kidney and
renal tumor. Intraoperative
high-resolution renal ultrasonography with a 7.5 MHz transducer was used to establish
and confirm tumor size, depth of invasion, and proximity to the renal hilar
vessels and the collecting system. The renal
hilar vessels were isolated but not occluded in all cases. Each tumor was biopsied with a 14gauge Tru-Cut
needle prior to initiation of cyroablation.Cryoablation was performed using
the Cryocare surgical system (Endocare Inc., Irvine, Calif, USA). Under ultrasound guidance, 1 or 2 cryoprobes
were placed directly into the identified lesion, and temperature sensor probes
were placed at the periphery of each mass to provide intraoperative monitoring
of adjacent renal parenchymal temperatures. In each case, the tumor margins were localized
with intraoperative ultrasound, allowing for precise placement of the cryoprobes. After cryoprobe placement, the tumor was
treated with 2 freeze cycles (−40C°
for 10–15 minutes/cycle) (see Figure 1). Each freeze cycle
was followed by an active thaw process. In the case of the partial nephrectomy,
the tumor was excised with a scalpel by tracing the edge of the ice ball.Figure 1
Open renal cryoablation. Cryoprobe with 2
temperature probes are seen.Perioperative data were evaluated including tumor size,
operative time, estimated blood loss, length of hospital stay, and preoperative
and postoperative creatinine.


## 3. Results

Eleven patients were treated with
cryoablation for 5 right renal tumors and 6 left renal tumors. The mean patient
age was 62.4 years (range 49–79 years). Tumors were located in the upper pole(n=6),
mid-kidney (n=2), and lower pole (n=3) with a mean and median tumor size
of 2.6 cm and 2.8 cm, respectively (range 1.2–4.3 cm). The mean operative time was 205 minutes (range 180–270 minutes),
blood loss 98.5 mL (range 40–250 mL), and
hospitalization 4.6 days (range 3–8 days). The procedure was successfully
completed in all patients without any major intraoperative or postoperative
complications.Biopsies of the 11 lesions confirmed renal cell carcinoma(n=7), oncocytoma (n=2), and angiomyolipoma (n=1), with one biopsy specimen
that was indeterminate. The patient that underwent cryoassisted partial nephrectomy
had negative margins.The mean preoperative creatinine was 1.43
mg/dL (range 1.2–1.9) and
postoperative creatinine was 1.67 mg/dL (range 1.5–2.5). The nadir creatinine was 1.57 mg/dL (range 1.3–2.1). All patients
were followed postoperatively with magnetic resonance imaging (MRI) at 3–6 month
intervals. Imaging these patients within
the first 3 months was not performed due to our prior experience with
inflammatory responses in the treated area that can lead to misinterpretation.
At a median follow-up of 43
months (4–59 months), 9
patients had no evidence of recurrence, 1 patient had an indeterminate area,
and 1 patient was lost to follow-up after 4 months.


## 4. Discussion

Cryoablation is a minimally invasive technique that has
emerged as an option for small renal masses with reduced morbidity compared to
partial nephrectomy. This technology
provides a nephron-sparing alternative that is curative by destruction rather
than excision of the renal mass [3].Tissue destruction from
cryoablative therapy occurs from sequential freezing and thawing of
tissues. Cellular destruction from the
freeze process results from complex direct and indirect physiologic mechanisms,
including direct physical disruption of the cellular membranes, proteins, and
intracellular organelles from ice crystals.
In addition, there are indirect effects such as microvascular
thrombosis, osmotic dehydration, and cellular anoxia during the freeze process,
which may also extend beyond the physical ice ball. The initial histologic change noted after a
cryoablative procedure is coagulative necrosis. Subsequently, chronic fibrosis with collagen
deposition results [2].Early animal studies by Nakada et al. utilizing and in
vivo rabbit renal cell cancer tumor model demonstrated that
thermosensor-monitored renal cryosurgery produces similar outcomes to
nephrectomy in terms of preventing metastatic disease [4]. Rodriguez et
al. published preliminary results of series of seven patients undergoing renal
cryoablation [5]. The estimated
blood loss averaged 111 mL and there were no perioperative complications. Six
of the 7 patients had a minimum of one follow-up computed tomography scan (mean
follow-up of 14.2 months) and each of these studies demonstrated partial
resolution of the lesion.Rukstalis
et al. reviewed a cohort of 29 patients that were treated with open
renal cryoablation since 1996 [6]. The median preoperative renal mass size was 2.2 cm, of which 22 were
solid renal masses and 7 were complex renal lesions. Five major adverse events occurred of which
only one event was directly related to the procedure. At median follow-up of 16 months, 1 patient
experienced a biopsy-proven local recurrence, and 91.3% of patients had a
complete radiographic response with only a residual scar or small nonenhancing
cyst. The authors concluded that open
renal cryoablation appeared safe for the destruction of solid or complex renal
masses, although rigorous radiographic, and clinical follow-up was required.Chen et al. reported their experience with laparoscopic
cryoablation of renal masses in 35 patients that underwent successful therapy
with minimal postoperative complications [7]. In their series, the mean operative time was
3 hours and mean estimated blood loss was 85 mL. At 11 months of follow-up, there were no
local or port site tumor recurrences. In
a similar study by Gill et al., 32 patients underwent laparoscopic renal
cryoablation. In this study, there were
no local tumor recurrences in this group of patients [8].Cryoablation is becoming an increasingly popular minimally
invasive technique for treating renal cell carcinoma and has been shown to
effectively treat renal and adrenal masses [8, 9]. This technique appears to be safe and
efficacious, with recurrence rate reported as low as 6.7%, and a 5year
cancer-specific survival rate of 100% for RCC [10–12].Patients with solitary kidneys or impaired
renal function may benefit from renal cryoablation as compared to partial
nephrectomy for several reasons.
Cryoablation may be associated with a lower risk for bleeding and may
obviate the need for hilar occlusion, thus preventing the detrimental effects
related to controlled ischemia. Our patients that were considered to be
appropriate candidates for cryoablation did not require hilar occlusion of
their solitary renal unit. While partial
nephrectomy can be selectively performed without warm ischemia, the patients in
our series had tumor characteristics that were not optimal for this procedure
without hilar occlusion.In our early experience with cryoablation
for patients with solitary kidneys, each patient underwent an open procedure in
order to minimize inadvertent injury and confirm adequate placement of the
cryoprobes. Since our initial
experience, we have continued our efforts to further decrease morbidity by
transitioning to a laparoscopic approach for suitable tumors in this cohort of
patients.Intraoperative ultrasound was essential in
delineating the intrarenal anatomy
and
the dimensions of the tumor [13].
Moreover, ultrasonography allows visualization of the ice ball to
confirm adequate treatment of the entire lesion. In the patient that underwent cryoassisted
partial nephrectomy, the tumor was excised following the freeze cycle with the
intention of minimizing blood loss, as hilar occlusion was not employed. Utilization of the edge of the ice ball
served as a guide for resection and facilitated complete excision of the mass
with minimal blood loss.Renal cryoablation has been
reported to target kidney tumors in a precise, safe, and reproducible manner. This technology offers the ability to treat
renal tumors in patients that require a maximal parenchymal sparing procedure,
such as patients with solitary kidneys. Renal cryoablation allows the accurate and
safe application of this surgical modality for the treatment of renal tumors
with emphasis on parenchymal sparing. Additionally,
the need for hilar occlusion of a solitary renal unit is completely obviated. Our intermediate follow-up data is promising
in terms of both cancer control and preservation of renal function. We do not routinely perform renal biopsies
following cryoablation due to the associated risks of bleeding and renal injury
in patients with solitary kidneys.
Instead, this practice can be reserved for patients with a suspicious
enhancing area on follow-up surveillance imaging studies. If a positive biopsy is obtained in this
instance, the options for surveillance, repeat cryoablation, or nephrectomy may
be considered. Our results are
consistent with other reports in the literature and demonstrate that renal
cryoablation is a feasible technique for the management of small renal masses
in patients with solitary kidneys. Additionally,
combined with a laparoscopic approach, cryoablation is an attractive minimally
invasive treatment option in such patients.



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