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The Current Status of Cryoablation for Renal Tumours
normal renal parenchyma. Replacement of the thin 17g needles can be
Figure 1: 3-D Illustration of Renal Cryoablation
performed with minimal risk of complication. Generally, two freeze cycles
of approximately 10 minutes each will be performed.
Method of Follow-up
A cryoablated tumour left in situ and the efficacy of the follow-up can be
evaluated only through imaging or biopsies. Besides the risk of significant
morbidity, biopsies of the kidney are low in sensitivity and specificity.
12
Follow-up of an ablative treatment with biopsies may be difficult due to
sampling error, especially in small recurrences, and carryies a higher risk
of complications when performed regularly. One of the mechanisms of
effect in cryoablation is aimed at complete vascular damage and,
consequently, ischaemic injury of the targeted tumour. Therefore, the
mainstay of the follow-up is perfusion-based imaging, as in contrast-
enhanced CT and MRI,
13
and focuses on absence of perfusion. Also, a
Figure 2: Galil Medical Patented 17-gauge Cryoablation
Needle with Iceball
diminishing in size of the lesion can be expected and is considered as a
non-vital sign of the ablated zone.
13–16
There is no indication for imaging within the first month after treatment.
During that period, enhancement patterns might be judged as being a
sign of persistent vital tumour. However, this can still be based on the
gradient changes in the vascularity. Therefore, first-time imaging is
advocated after three months, and further imaging at six months and
every six months thereafter for the first three years. This follow-up
schedule is based upon the European Association of Urology (EAU)
guidelines for T1 and T2 renal cell cancer.
17
This also includes regular
chest X-ray and blood-test examination. In the event of no malignancy renal cryosurgery.
21,22
For cancer-specific outcome these data should be
being identified at biopsy, the possibility of reducing the frequency of read carefully because they contain pooled data representing both
follow-up controls is open for discussion. malignant and benign masses. Weld et al. reported on 31 patients with
36 tumours and completed three-year follow-up. Biopsy revealed 22
It is important to realise that contrast-enhanced imaging in renal malignant masses. The cancer-specific survival rate was 100%, and only
function impairment is associated with risks. This is not only limited to one patient (4.5%) demonstrated return of abnormal enhancement
contrast CT, but also to gadolinium-based contrast MRI.
18
Early within the cryoablated lesion during follow-up, suggesting tumour
experiments show that it is possible to determine the existence of flow recurrence. The largest series is described by Gill et al., reporting a series
in ablated lesions with contrast-enhanced ultrasound.
19
This could be an of 56 patients revealing biopsy-confirmed malignant disease in 36
alternative to imaging in the follow-up of patients with significant renal patients. The cancer-specific success rate was 94%. The two tumours
function impairment. that were not successfully ablated underwent further surgery.
Percutaneous versus Laparoscopic Renal Cryoablation Long-term Follow-up
Indications for percutaneous image-guided renal cryoablation are limited Limited reports on long-term follow-up are available. Recently, two
by tumour location. Posterior-located tumours are particularly suited to a studies have been published showing their data with a prolonged follow-
percutaneous approach. Image-guided cryoablative techniques for up of five years after open or laparoscopic renal cryosurgery.
23,24
In these
tumours that are anterior-located, hilar or near to adjacent structures, studies a variety of cryoprobes and machines were used. Davol et al.
such as the bowel and ureter, are at greater risk of complications due to reported a series of 48 patients, of whom 32 manifested a biopsy-
collateral injury. In a retrospective study the efficacy and complications of confirmed renal cell cancer, with a median follow-up of 64 months
laparoscopic cryoablation (LCA) and percutaneous cryoablation (PCA) (range 36–110) and a median tumour size of 2.6cm. The cancer- specific
were compared.
20
There were significantly more anterior tumours treated survival rate was 100%, with a cancer-free survival rate of 84.3% after a
in the LCA group (31 anterior, 12 posterior) compared with the PCA single cryoablation procedure. The cancer-free survival rate was 87.5%
group (one anterior, 51 posterior). In the LCA group – which had a mean after a second cryoablation procedure and 96.8% after surgical salvage
follow-up of seven months – there were no recurrences, whereas in the procedures. Hegarty et al. presented their results in 60 patients with at
PCA group – with a follow-up of 16 months – there were two least five years of follow-up after a laparoscopic-assisted cryoablation.
recurrences (3.8%). The PCA group had only seven minor complications Within a median follow-up of 72 months, the cancer-specific survival rate
(13.5%). The LCA group had four complications of which three were was 100%. Three patients (6.7%) experienced a local tumour recurrence
major, including one death from aspiration pneumonia. There was a that required further treatment.
significant difference in estimated blood loss in favour of the PCA group.
Complications
Intermediate-term Follow-up The most common minor complication is paraesthesia at the site of larger
Several groups have reported on their intermediate-term follow-up of probe insertion through the skin. Most of these painful sensations and
EUROPEAN GENITO-URINARY DISEASE 2007 49
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