Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5209_Библиотеки_им_академика_М_И_Перельмана.pdf
32
M. A. Awad et al.
peratures. A study by Carey and Leveilee demon-
strated promising results using this method, with
100% clinical success achieved in treating tumors
up to 5 cm in diameter [63]. Experimental imaging techniques like real-time contrast-enhanced
ultrasonography [64], magnetic resonance thermometry [65], and magnetic resonance elastography [66] have shown potential but require
further evaluation in clinical settings. Ultimately,
the success of renal lesion ablation with RFA
depends on precise probe placement, feedback
from the generator and thermal probes, and conrmation of the absence of contrast during percutaneous axial image-guided RFA.
Surgical Technique ofPercutaneous
Renal Cryoablation
andRadiofrequency Ablation
Percutaneous renal tumor ablation procedures
can be performed under conscious sedation with
local anesthesia or general endotracheal anesthesia, depending on the preference of the treating
physician. General anesthesia allows for better
control of respiration during probe placement
and tumor biopsy, potentially leading to improved
targeting accuracy and overall outcomes [67]. On
the other hand, conscious sedation minimizes the
procedure’s morbidity and duration. The patient
receives intravenous prophylactic antibiotics
before the procedure. They are positioned either
prone or in a modied ank position on the CT
gantry, depending on the tumor location. CT
guidance is the most commonly used technique
for targeting the tumor during the procedure,
although ultrasound and magnetic resonance
guidance have also been reported as alternative
methods [68, 69].
A non-contrast CT image is initially obtained
to conrm the size and position of the tumor in
the prone or lateral position. Subsequently, a contrast-enhanced CT image may be acquired to better visualize and delineate the tumor. To assist
with needle placement, a radiographic grid is
placed on the patient’s skin. Under CT guidance,
a 20-gauge “nder needle” or access sheath is
inserted near the expected tumor location. Its
position is conrmed through repeated imaging.
Using the nder needle as a guide, the ablation
probe(s) is then positioned to treat the tumor. The
number of probes and the treatment duration are
determined based on the size of the lesion following the manufacturer’s recommendations. Serial
imaging is performed to ensure proper placement
of all treatment proves or tines. Preferably, a preprocedure needle biopsy should be conducted to
provide pathologic diagnosis and guide subsequent follow-up. However, if a biopsy has not
been performed, an 18-gauge core biopsy needle
should be obtained before initiating therapy and
sent for permanent histopathological analysis [5].
It is important to position the treatment probes
into the tumor before obtaining the biopsy to
avoid obscuring the visualization of the tumor
with a perinephric hematoma. The positioning
and adjustments of the probes and biopsy needle
are performed with breath holding to maintain
consistency in kidney position during each
sequential needle pass.
Cryoablation
During CA, the efcacy of the treatment is monitored through imaging of the ablation zone. The
cryoprobe tips reach extremely low temperatures
ranging from −140°C to −190°C, with a temperature gradient that decreases to 0 °C at the
edge of the iceball. At a distance of 3.1mm inside
the edge of the iceball, temperatures less than
−20°C are reached [70]. Tumor cell death is reli-
ably achieved at target temperatures of −40°C
[70], so the iceball should extend 5–10 mm
beyond the tumor margin to ensure complete
treatment. The iceball appears as a distinct
hypodense zone on CT imaging (Fig. 3.3). To
achieve more complete tissue necrosis, two
freeze-thaw cycles are typically performed during CA [71]. The duration of the freeze cycle can
vary, but a common practice is to use a 10-minute
freeze cycle for the initial cycle and a shorter
duration (6–8min) for the second cycle. Animal
studies have shown inadequate necrosis at 5minutes and increased tissue fracture at 15min, making 10-min freeze cycles an optimal compromise
for sufcient tumor necrosis and fewer complications [72]. Each freeze cycle is followed by either
an active (helium-based) or passive thaw. The
choice between active and passive thawing is still
3 Focal Ablative Therapy forLocalized Kidney Cancer
33
Fig. 3.3 (a) External
view of four cryoprobes
during the freeze cycle.
(b) CT procedural
monitoring of the iceball
during percutaneous
cryoablation of a 2.7cm
tumor with three
cryoprobes (different
patients)
a
b
debated, but some experts suggest an active thaw,
at least during the second cycle, to reduce operative time and facilitate prompt management of
post-treatment bleeding [30]. After the second
cycle thaw, the probe is gently twisted, and if
there is no resistance, it is removed atraumatically. A contrast-enhanced CT scan is performed
after treatment to evaluate the completeness of
ablation and to rule out any complications that
may have arisen. The imaging helps conrm the
success of the procedure and ensures that the
desired treatment outcome has been achieved.
Radiofrequency Ablation
During RFA, the efcacy of the treatment is monitored through the measurement of tissue temperature or impedance. This is achieved using
either single multitoned probes with incorporated
thermistors or multiple single-shaft probes that
measure tissue impedance as the endpoint. In our
institutions, a 14-gauge Starburst XL RFA probe
is used, and its position is adjusted to ensure
complete coverage of the lesion and a peritumoral margin of at least 5mm. To minimize radiation exposure, conrmatory scans are limited to
3–4mm images centered around the target lesion
using a lower current (70mA) compared to standard helical CT (150mA) [73]. Ablation cycles
of 5, 7, and 8min are delivered at a target tem-
perature of 105 °C for tine deployments of <2,
2–3, and 3–4cm, respectively. After a cool- down
period of 30s, a second cycle of similar duration
is performed. During the cool-down cycles, the
passive tissue temperature in each quadrant
should be at least 80°C, indicating the absence of
a signicant heat sink. Contrast- enhanced helical
CT is performed after treatment to assess the
completeness of ablation and identify any complications. If inadequately treated areas are
found, the RFA probe is repositioned, and the
ablation is repeated. The probe tract may also be
ablated during probe withdrawal depending on
the manufacturer’s instructions. For larger
lesions, nonconducting temperature probes
placed at the tumor’s peripheral and deep margins can be used for active temperature monitoring [63]. Alternatively, multiple individual probes
can be used in overlapping ablations [74]. Patients
who undergo percutaneous CA or RFA are typically discharged on the same day if under general
anesthesia or conscious sedation, while those
with signicant comorbidities or complications
may require overnight admission.
Imaging Interpretation ofSuccess
In situ ablation procedures do not provide pathological margins for evaluation. Instead, the effectiveness of treatment is assessed through imaging
34
M. A. Awad et al.
characteristics. The absence of contrast enhancement on follow-up CT or MRI scans is generally
indicative of successful tissue destruction and
treatment efcacy [75, 76]. The rst post-ablation imaging is typically conducted 6–12weeks
after the procedure. If any portion of the treated
lesion shows persistent enhancement on the initial imaging, it is classied as an incomplete
ablation, and repeat ablation is scheduled
(Fig.3.4). On the other hand, if a lesion initially
shows complete loss of contrast enhancement but
later exhibits enlargement of the lesion and/or
Fig. 3.4 Post-RFA MRI
demonstrating central
and posterior
coagulation necrosis,
however, with residual
peripheral nodular
arterial enhancement
along the medial,
anterior, and lateral
aspect
contrast enhancement, it is considered a local
tumor recurrence or progression [77]. These
imaging ndings guide further management decisions and treatment strategies.
Following CA or RFA, the appearance of
lesions on follow-up imaging provides valuable
information. CA-treated lesions are typically
seen as areas of hypoattenuation that are no longer enhancing (Fig. 3.5) [78, 79]. In contrast,
RFA-treated lesions often show minimal postablative contraction and display a distinct brotic
halo or circular demarcation around the treatment
a
Fig. 3.5 (a) CT of the original tumor, showing 1.3cm enhancing mass in the right upper pole. (b) Repeat CT of the
tumor 3months post-cryoablation, no longer enhancing
b
3 Focal Ablative Therapy forLocalized Kidney Cancer
35
a
Fig. 3.6 (a) CT scan showing a left lower pole enhancing renal mass. (b) CT scan 1-year post-RFA demonstrating the
characteristic halo appearance around the ablation zone (red arrow)
zone (Fig.3.6). This brotic response represents
a foreign-body giant cell reaction [80]. Regardless
of the treatment modality or enhancement characteristics, any enlargement of a lesion should be
considered indicative of tumor recurrence. In
such cases, it is important to strongly consider
performing a biopsy and/or determining the
appropriate course of treatment, which may
involve observation, repeat ablation, or surgical
removal. Monitoring changes in lesion size and
appearance on follow-up imaging is crucial for
accurate assessment of treatment response and
guiding subsequent management decisions.
b
protocol which is at 1-year and then annually
thereafter for 5 years. Then, informed/shared
decision-making should guide surveillance decisions beyond 5years.
Follow-up after TA is not specically mentioned in the most recent EAU guidelines;
instead, a risk-adapted follow-up based on the
risk of recurrence according to the Leibovich
model score for clear cell RCC (ccRCC) [81] and
on the University of California, Los Angeles integrated staging system (UISS) for non-ccRCC are
proposed [82]. Alternative models based on
national/regional recommendations can be used
[10]. For patients with Low-risk of recurrence
Recommended Imaging Follow-Up Protocol
As tumor stage and nuclear grade are the most
important factors for recurrence after TA, most
recent AUA and EAU guidelines recommend/
propose classifying patients with malignant renal
masses into risk groups for follow-up. For
patients who undergo renal tumor ablation, the
pre-ablation tumor biopsy histology could impact
the risk group classication [10, 13]. The AUA
guidelines’ recommendation for the follow-up
protocol after renal tumor ablation involves CT
or MRI scan with and without intravenous contrast within the rst 6months (if not contraindicated) without specic preference for one test
over another as a primary imaging modality or
during follow-up [13]. Subsequent follow-up
scans are performed according to recommendations for the “intermediate risk group” follow-up
(ccRCC Leibovich score 0–2 or non-ccRCC
pT1a-b, pNx-0, M0 and histological grade 1 or
2), imaging is recommended at 6, 18, and
30months and afterwards once every 2years. For
patients at Intermediate risk of recurrence
(ccRCC Leibovich score 3–5 or non-ccRCC
pT1b pNx–0 and/or histological grade 3 or 4) CT
at 6,12 and thereafter once a year up to 5years
[10]. Similar to the AUA guideline, follow-up
surveillance beyond 3 and 5years for low- and
intermediate-risk proles is guided by clinical
counseling, competing risk of death, and patient
wishes.
As only the clinical stage is available after TA,
others have proposed to classify tumors treated
by ablation in reduced risk (cT1a and nuclear
grade 1–2) and elevated-risk (cT1b stage or
nuclear grade 3–4) of recurrence with a similar
intensity of image to the EAU guidelines [83].
36
M. A. Awad et al.
Neither AUA nor EAU The guidelines do not
indicate a preference for MRI or CT as the primary imaging modality for routine follow-up
[13]. Ultrasonography is generally not recommended for evaluating lesions after ablation
unless specic protocols for contrast- enhanced
ultrasonography are in place.
Emerging New Ablative Modalities
Microwave Ablation
Microwave ablation (MWA) is a thermal ablation
technique that uses semiexible probes inserted
directly into the target lesion, similar to RFA.It
operates within the range of 900 MHz to
2.45 GHz in the electromagnetic spectrum and
creates rapid oscillation of water ions in the tissue, generating frictional heat. The penetration
depth and head production depend on the water
content of the target tissue, which can be challenging to predict accurately in the heterogeneous environment of the kidney [84, 85]. MWA
can achieve treatment temperatures (>60 °C)
more quickly than RFA and is not limited by tissue charring and desiccation. These characteristics may lead to more efcient treatment times
and potentially make MWA less susceptible to
the heat sink phenomenon, whereby nearby blood
vessels dissipate heat and reduce the effectiveness of the treatment [86, 87].
While MWA has been successfully utilized for
percutaneous treatment of liver tumors, its application in managing renal tumors is still in its
early stages. Initial studies have shown promising
results, with complete and uniform tissue necrosis observed in renal lesions with suspected RCC
as large as 5.7cm in 10 patients who underwent
MWA at the time of radical nephrectomy [88].
Subsequent studies have reported a success rate
over 90% for treating pT1a and pT1b tumors [89,
90]. In a recent propensity score-analysis study
comparing RFA to MWA, there was no signicant difference in primary efcacy between the
two modalities [91]. Furthermore, in a direct
comparison with partial nephrectomy in another
propensity-matched study with a median followup of 41months, MWA demonstrated compara-
ble local tumor progression, cancer- specic
survival, and distant metastasis. However, MWA
had worse disease-free and overall survival [92].
Despite the theoretical advantages of MWA
over other thermal ablation techniques like CA
and RFA, there is a need for more follow-up data
and further investigation. Larger prospective
studies with longer-term follow-up are necessary
to determine the optimal tumor characteristics,
assess risks, and evaluate morbidity associated
with MWA.
Irreversible Electroporation
Irreversible electroporation (IRE) is a nonthermal method used for ablation of living tissue,
offering potential advantages over other techniques like RFA and CA.IRE involves applying
an electric eld to cells, creating nanoscale
probes in cellular membranes. The outcome can
be reversible or lethally irreversible electroporation, depending on the voltage applied. IRE utilizes a series of electrical pulses delivered through
single or multiple electrodes to increase cell
membrane permeability, ultimately leading to
cell death [93]. IRE has a nonthermal effect that
preserves important structures such as the extracellular matrix, tissue scaffolding, ductal structures, and large blood vessels [93, 94]. Due to its
potential to overcome the limitations of thermal
ablation techniques, there is signicant interest in
applying IRE for the ablation of renal tumors.
However, the effectiveness of IRE in ablating
liver and prostate tissue cannot be directly extrapolated to the kidney due to the kidney’s unique
characteristics, such as its complex arterial blood
supply, collecting system, and varying concentrations of urinary solutes. In addition, in order for
the IRE to be successful, the needle electrodes
have to be parallel to each other, which is easier
to do in xed organs such as the prostate. Initial
studies on porcine kidneys using laparoscopic
and percutaneous IRE electrodes demonstrated
the absence of cellular viability immediately
after treatment, followed by necrosis, inammation, cellular contraction, and brosis in subsequent days [95].
Clinical experience with percutaneous IRE for
renal tumors is extremely limited. A study by
3 Focal Ablative Therapy forLocalized Kidney Cancer
37
Diehl et al. demonstrated the safety of IRE in
treating SRM in solitary kidneys but did not
report oncologic outcomes [96]. Another study
by Canvasser etal. reported on 36 tumors in 35
patients who underwent IRE, showing a high initial treatment success rate and promising localrecurrence- free survival at the 2-year mark [97].
Given the limited data on IRE, its use in this context should be considered investigational. Further
research and larger studies are needed to better
understand the efcacy, safety, and long- term
outcomes of IRE in treating renal tumors.
Radiation Therapy
Historically, radiation therapy was not considered effective for the treatment of RCC.It remains
uncertain whether poor outcomes with conventional radiation systems were due to inherent
radiation resistance or limitations in radiation
delivery. There are several technical challenges
associated with treating kidney tumors, including
limited radiation tolerance of normal kidney tissue, scatter radiation causing damage to surrounding tissues, and difculty in precisely
localizing the target.
Stereotactic body radiation therapy (SBRT) is
a modern treatment method that precisely delivers a high dose of radiation to the target using a
single dose or a small number of fractions [98].
Unlike conventional radiation techniques, SBRT
employs three-dimensional coordinates to compensate for respiratory movement and radiation
scatter. It uses real-time tracking and correction
systems to ensure accurate radiation delivery
without interrupting treatment or repositioning
the patient [99]. This allows for the application of
high-dose radiation precisely to the tumor, effectively ablating the mass without compromising
overall renal function [99].
Early studies on animal models and small
patient cohorts demonstrated the feasibility and
safety of SBRT for renal tumors. These studies
showed complete necrosis within the treated zone
and no collateral damage to adjacent tissues [99,
100]. A systematic review of SBRT studies for
primary RCC showed a high rate of local control
(84–100%) and low rates of adverse effects
(21.4% grade 1–2 non-renal toxicities, and 3.8%
grade 3 or higher) [101]. Recently, a multiinstitutional study done by the International
Radiosurgery Consortium of the Kidney
(IROCK) included 190 patients with primary
RCC who underwent SBRT with a median follow-up of 5years. Results showed a local failure
of 5.5% [102].
Studies have further investigated the radiographic appearance and response of RCC treated
with SBRT. Interpretation of the early response
to SBRT can be challenging, as the radiographic
changes may differ from those seen with thermal
ablation. However, overall response rates have
been promising, with stability in tumor size, partial responses, and occasional complete response
reported [103].
While the responsiveness of RCC to SBRT
challenges its reputation as radioresistant, its use
should still be considered experimental. There is
currently no consensus on optimal dose fractionation, technique (with or without ducial markers), or criteria for interpreting imaging. Further
improvement in treatment protocols and welldesigned prospective trials are needed to establish the role of SBRT in the treatment of RCC.
Oncological Outcomes
Interpreting and comparing the oncologic success of thermal ablation for RCC is complicated
by several confounding variables in the literature.
These include small cohort sizes, short follow-up
periods, the inclusion of patients with benign
masses, the absence of pre-ablation biopsy, the
inclusion of patients with factors that may affect
RCC recurrence, such as cancer hereditary syndromes, the use of different technologies, and
variable denitions of recurrence. However, as
the eld of thermal ablation matures, the quality
of evidence has improved, with most series now
controlling for these variables. In a head-to-head
comparison of RFA and partial nephrectomy for
sporadic unilateral T1a RCC, 5-year actual local
recurrence-free survival, overall disease-free survival, and progression-free survival were statistically similar between the two cohorts when
considering patients who required a second ablation for incomplete primary [104]. Similarly, a
separate comparison of thermal ablation (CA and
38
M. A. Awad et al.
RFA) to partial nephrectomy showed no difference in recurrence-free survival among the different modalities at 3years of follow-up [105].
The intermediate and long-term results of CA
and RFA indicate that these thermal ablation
techniques are effective and durable for treating
small cortical neoplasms. As a result, the indications for thermal ablations have expanded. The
AUA guidelines now recommend that physicians
consider thermal ablation as an alternative
approach for managing cT1a renal masses that
are less than 3cm in diameter [5]. However, it is
important to note that tumor recurrence or persistence may be more likely with thermal ablation,
and repeat ablation may be necessary in some
cases. This recommendation highlights the growing acceptance and recognition of thermal ablation as a viable option for smaller renal masses.
Local Recurrence-Free Survival
Local recurrence-free survival (LRFS) in thermal
ablation procedures is commonly dened as the
presence of residual disease in the treated kidney
after the primary ablation. According to a metaanalysis done by the AUA 2021 SRM guidelines
panel for studies with follow-up of 48 months
(±12months), LRFS favored surgical extirpation
when compared to thermal ablation (risk ratio
0.55, 95% CI 0.33–0.91). However, these differences largely disappeared when the thermal ablation groups included patients who underwent
repeat salvage ablations (risk ratio 0.97, 95%
0.47–2) [5]. Similarly, a meta-analysis of 147
studies reported that partial nephrectomy had a
higher LRFS compared to thermal ablation at a
median follow-up of 60 months in extirpative
cohorts and 48.6months in the thermal ablation
cohorts (90.9% vs. 93%). However, this difference became insignicant when considering the
LRFS after a subsequent salvage ablative procedure, which improved the efcacy of thermal
ablation to 97–100% [4]. Furthermore, Katsanos
et al. investigated 587 patients with SRM who
underwent thermal ablation versus nephrectomy
and found no signicant difference in the local
recurrence rate at 5years (3.6% vs. 3.6%) [106].
Metastasis Recurrence-Free,
andCancer-Specic Survival
The meta-analysis by Pierorazio etal. found no
signicant difference in metastasis-free survival
(MFS) when comparing partial nephrectomy
(99%, IQR 97.9–100) to thermal ablation for
renal tumors (97.6%, IQR 93–100). Furthermore,
no signicant difference was found in cancerspecic survival (100%, IQR 99.3–100) in the
partial nephrectomy cohorts versus (95.4%, IQR
92–98) in the thermal ablation cohorts [4].
Several studies with intermediate- to long-term
follow-up have reported outcomes for RFA and
CA and have provided data beyond 5years and
up to 10years of follow-up [104, 107–110]. The
data collectively suggest that the outcomes of
ablative procedures remain durable over time.
Overall Survival
Ablative procedures are often performed on older
patients with more comorbidities compared to
those undergoing extirpative surgery, as highlighted in the meta-analyses by Pierorazio and
Uhlig [4, 111]. As a result, the mean overall sur-
vival rate following ablative procedures tends to
range from 75% to 85% at 5years and decrease
to 54% to 64% at 10years, according to several
studies [42, 109, 112, 113]. These ndings suggest that long-term survival of ablative procedures may be lower, likely due to factors related
to patient age and comorbidities.
Eect ofTumor Size onAblation
Outcomes
Tumor size is an important factor affecting the
success of ablative procedures, as indicated by
long-term follow-up data. Best et al. observed
that in patients undergoing RFA, the 5-year overall LRFS was 95% for tumors smaller than 3cm
but only 78% for tumors 3cm or larger [107].
Johnson etal. reported disease-free survival after
RFA for renal tumors less than 3cm to be 97% at
6years follow-up compared to 68% for tumors
more than 3cm in size. They also noticed a signicant decrease in MFS and CSS for tumors
more than 3 cm [108]. Similarly, Psutka etal.
3 Focal Ablative Therapy forLocalized Kidney Cancer
39
reported a 5-year LRFS and overall disease-free
survival of 96.1% and 91.5%, respectively, for
RFA-treated tumors smaller than 4 cm (T1a),
compared to 91.9% and 74.5% for tumors larger
than 4 cm (T1b) [109]. Tanagho etal. demonstrated a 6-year overall disease-free survival of
80% after CA, with a tumor size of 2.6 cm or
greater being the only predictor of oncologic failure [110]. Building on this nding, Caputo etal.
evaluated the treatment outcomes of T1b tumors
(>4 and <7cm) using CA versus partial nephrectomy and found a 23% recurrence rate with CA
compared to partial nephrectomy, despite similar
overall tumor sizes in both cohorts (4.3cm vs.
4.6 cm) [112]. Similarly, Pickersgill et al.
reported their 10-year experience with CA for
renal tumors in 308 patients. In a multivariate
analysis, they found increasing renal tumor size
to be a signicant predictor of disease progression (hazard ratio 1.32 per 1cm increase in size,
p=0.001) [114].
Cryoablation Versus Radiofrequency Ablation
Direct data comparing CA and RFA counterparts
are limited. The lack of well-dened radiologic
and pathological endpoints, along with variations
in patient selection, tumor characteristics, techniques, and approaches, as well as inherent bias
toward a specic ablative modality, contribute to
the challenge of making direct comparisons.
Nevertheless, a meta-analysis by El Dib etal. in
2012 comparing CA to RFA, included 31 case
series (20 CA, 11 RFA), found no difference in
clinical efcacy (89% vs. 90%, respectively)
[115]. A more recent meta-analysis by Shi etal.
in 2022 that only included RCTs, cohort studies,
or case-control studies showed no difference in
primary efcacy, 5-year survival rate, complications, and changes in serum creatinine. However,
the analysis showed a higher rate of LRFS for CA
compared to RFA.This difference was not apparent in a subanalysis when only comparing outcomes in T1a tumors [116]. These ndings
suggest that CA and RFA have similar effectiveness in achieving local control of renal tumors at
least in T1a renal tumors.
Complications
In terms of perioperative outcomes, a metaanalysis done by Pierorazio etal. showed that
thermal ablation has the most favorable results
when compared to radical nephrectomy (RN) and
partial nephrectomy (PN). It had fewer conversions to open surgery, shorter hospital stay, less
estimated blood loss, and fewer blood transfusions [4]. The analysis also revealed that the rate
of major urologic complications was 4.9% for
CA and 6% for RFA. The occurrence of major
nonurological complications was 5% for CA and
4.5% for RFA.The risk of major urologic complications was lower with ablative techniques
compared to laparoscopic or open PN [4].
Although the majority of complications associated with renal ablation are minor, with major
complications occurring in around 2% of cases, a
signicant proportion of complications (up to
20%) may require hospital readmission, procedural intervention, or blood transfusion [106].
Notably, a study by Schmit et al. demonstrated
that percutaneous ablation carries a higher risk of
complications, particularly in cases involving
high-complexity tumors (nephrometry score of
10–12) with about 14% risk of major complications [117].
The most common perioperative complication associated with percutaneous ablation procedures is intraoperative or postoperative
hemorrhage, occurring in a signicant percentage of patients. Studies have reported hemorrhage rates ranging from 11% to 27% for renal
ablative procedures [118]. Transfusion rates for
hemorrhage during percutaneous ablation are
approximately 3.2% for CA and 2.4% for RFA
[4]. However, with increasing experience and
improved techniques, the risk of postoperative
blood transfusion has been decreasing in recent
series, with rates ranging from 0% to 2% [119].
The primary risk factor for hemorrhage is the use
of multiple probes for treating larger renal
masses [119]. It is important to allow adequate
time for probe thawing during CA to minimize
the risk of tumor fracture and subsequent hemorrhage. Bleeding during needle placement can
often be controlled by initiating ablation, espe-
40
M. A. Awad et al.
cially with the coagulative nature of RFA. If
bleeding persists after ablation, selective angioembolization may be considered.
In the past, pain or paresthesia at the percutaneous probe insertion site was a common complication following renal tumor ablation, affecting
up to 8% of patients [120]. However, advancements in cryoprobes have led to improved thermal insulation along the probe shaft, resulting in
a decrease in freezer burns compared to previous
generations. For RFA, the active part of the probe
is limited to the most distal aspect to prevent
inadvertent nerve damage. Tract ablation during
RFA should only be performed briey to remove
the probe from the kidney and surrounding
Gerota’s fascia, reducing the risk of nerve injury.
Electrical skin burns are a rare occurrence after
RFA and are typically associated with the grounding pads. To prevent such burns, it is recommended to place the grounding pads at the exact
same level on the patient’s posterior thigh [121].
By positioning the pads perpendicular to the long
axis of the thigh, the surface area of the energy
dissipation is increased, minimizing the likelihood of skin burns. Proper pad placement ensures
that the energy returning to the generator follows
the shortest arc.
To minimize complications associated with
damage to surrounding intra-abdominal organs
during renal tumor ablation, several measures
can be taken. Appropriate patient selection, and
preoperative planning play crucial roles in this
regard. Cross-sectional imaging is vital to determine if patients is appropriate for percutaneous
ablation. In cases where adjacent organs are a
concern, additional imaging can be performed
with the patient in different positions to plan a
suitable needle path. Percutaneous treatment is
ideal for patients with posterior or lateral tumors,
tumors located at least 5mm away from the ureteropelvic junction or renal pelvis, and tumors
with a minimum distance of 10mm from the surrounding bowel.
Urothelial damage can manifest as minor
hematuria, hematuria with signicant clots, or
urinary tract obstruction. Hematuria typically
requires conservative management unless there is
severe bleeding, in which case selective angioembolization may be considered. Permanent urothelial damage can lead to calyceal or ureteral
obstruction, particularly if the damage occurs at
the ureteropelvic junction or distally [122]. In
severe cases, urinary tract damage may result in
the formation of a perirenal urinoma or cutaneous urinary stula. Conservative management or
the insertion of an indwelling ureteral stent can
be considered for patients with ureteral obstruction or urine leakage from the collecting system.
Patients with signicant urinoma accumulation
may require the placement of a percutaneous
drain.
It is possible to inadvertently cause injury to
the pleural cavity, leading to the development of
pneumothorax or hemothorax. This typically
occurs when probes are placed above the twelfth
rib to treat upper pole lesions. These complications are usually identied either during the procedure itself, as patients may experience difculty
breathing, or through percutaneous access imaging performed as part of routine tumor treatment.
If a simple pneumothorax is detected, it can be
managed by aspirating the air from the pleural
space using a small needle at the end of the procedure. However, if the pneumothorax is large or
persistent, the insertion of a chest tube may be
necessary. Following the procedure, patients
should be monitored for symptoms such as chest
pain or shortness of breath as these may indicate
the presence of pneumothorax. In such cases, an
upright chest x-ray should be promptly performed to conrm the diagnosis and guide appropriate treatment.
During percutaneous treatment of posterior
tumors in the kidney, there is a risk of damaging
the nerves that run along the posterior abdominal
wall. This can result in temporary neuralgia or
neuropraxia [123, 124]. However, these complications can be prevented by positioning the
patient in such a way that the tumor falls away
from the body wall or by using hydrodissection
to create a space between the kidney and the body
wall [124].
3 Focal Ablative Therapy forLocalized Kidney Cancer
41
Conclusion
There is development of new treatments and
improvement of established treatment modalities
for SRMs. TA has been present for more than
30 years now. Advances in technology have
expanded the use of TA and recent outcomes
show promising results. TA is predominantly
indicated for SRMs with a benet for patients
where surgical intervention is contraindicated.
Although PN is still the gold standard nephronsparing treatment, long-term outcomes for
patients who undergo TA are relatively comparable those with PN. RMB continues to play an
informative role in the decision-making process
for patients and physicians and is vital in pathological diagnosis prior to TA.Patients diagnosed
with SRM must have a detailed discussion on the
management including surveillance, minimally
invasive options, and surgery, as there is no doubt
that the role of TA will continue to expand.
References
1. Siegel RL, Miller KD, Wagle NS, Jemal A.Cancer
statistics, 2023. CA Cancer J Clin. 2023;73(1):17–48.
2. Chen DY, Uzzo RG.Evaluation and management of
the renal mass. Med Clin. 2011;95(1):179–89.
3. Huang WC, Elkin EB, Levey AS, Jang TL, Russo
P. Partial nephrectomy versus radical nephrectomy
in patients with small renal tumors—is there a difference in mortality and cardiovascular outcomes? J
Urol. 2009;181(1):55–62.
4. Pierorazio PM, Johnson MH, Patel HD, Sozio SM,
Sharma R, Iyoha E, et al. Management of renal
masses and localized renal cancer: systematic review
and meta-analysis. J Urol. 2016;196(4):989–99.
5. Campbell SC, Clark PE, Chang SS, Karam JA,
Souter L, Uzzo RG.Renal mass and localized renal
cancer: evaluation, management, and follow-up:
AUA guideline: part I.J Urol. 2021;206(2):199–208.
6. Abouassaly R, Finelli A, Timilshina N, Alibhai
SM. Treatment trends for renal cell carcinoma
in a population-based tumor registry: the potential underuse of partial nephrectomy. J Urol.
2009;181(4S):76–7.
7. Desai MM, Aron M, Gill IS.Laparoscopic partial
nephrectomy versus laparoscopic cryoablation for
the small renal tumor. Urology. 2005;66(5):23–8.
8. Bhindi B, Mason RJ, Haddad MM, Boorjian SA,
Leibovich BC, Atwell TD, et al. Outcomes after
cryoablation versus partial nephrectomy for sporadic
renal tumors in a solitary kidney: a propensity score
analysis. Eur Urol. 2018;73(2):254–9.
9. Stern JM, Gupta A, Raman JD, Cost N, Lucas S,
Lotan Y, et al. Radiofrequency ablation of small
renal cortical tumours in healthy adults: renal function preservation and intermediate oncological outcome. BJU Int. 2009;104(6):786–9.
10. Ljungberg B, Albiges L, Abu-Ghanem Y, Bedke
J, Capitanio U, Dabestani S, et al. European
Association of Urology guidelines on renal cell carcinoma: the 2022 update. Eur Urol. 2022;82:399.
11. Frank I, Blute ML, Cheville JC, Lohse CM, Weaver
AL, Zincke H. Solid renal tumors: an analysis of
pathological features related to tumor size. J Urol.
2003;170(6 Pt 1):2217–20.
12. Duchene DA, Lotan Y, Cadeddu JA, Sagalowsky
AI, Koeneman KS. Histopathology of surgically
managed renal tumors: analysis of a contemporary
series. Urology. 2003;62(5):827–30.
13. Campbell SC, Uzzo RG, Karam JA, Chang SS,
Clark PE, Souter L.Renal mass and localized renal
cancer: evaluation, management, and follow-up:
AUA guideline: part II.J Urol. 2021;206(2):209–18.
14. Motzer RJ, Jonasch E, Agarwal N, Alva A, Baine M,
Beckermann K, etal. Kidney cancer, version 3.2022,
NCCN clinical practice guidelines in oncology. J
Natl Compr Cancer Netw. 2022;20(1):71–90.
15. Fujimori M, Yamanaka T, Sugino Y, Matsushita N,
Sakuma H. Percutaneous image-guided thermal
ablation for renal cell carcinoma. Interv Radiol
(Higashimatsuyama). 2020;5(2):32–42.
16. Venkatesan AM, Wood BJ, Gervais
DA.Percutaneous ablation in the kidney. Radiology.
2011;261(2):375–91.
17. Ali SN, Tano Z, Landman J. The changing role
of renal mass biopsy. Urol Clin North Am.
2023;50(2):217–25.
18. Patel HD, Johnson MH, Pierorazio PM, Sozio SM,
Sharma R, Iyoha E, etal. Diagnostic accuracy and
risks of biopsy in the diagnosis of a renal mass suspicious for localized renal cell carcinoma: systematic
review of the literature. J Urol. 2016;195(5):1340–7.
19. Marconi L, Dabestani S, Lam TB, Hofmann F,
Stewart F, Norrie J, et al. Systematic review and
meta-analysis of diagnostic accuracy of percutaneous
renal tumour biopsy. Eur Urol. 2016;69(4):660–73.
20. Renshaw AA, Powell A, Caso J, Gould EW.Needle
track seeding in renal mass biopsies. Cancer
Cytopathol. 2019;127(6):358–61.
21. Van Poppel H, Becker F, Cadeddu JA, Gill IS,
Janetschek G, Jewett MA, etal. Treatment of localised
renal cell carcinoma. Eur Urol. 2011;60(4):662–72.
22. Lomoschitz FM, Stummer H.Applied change management in interventional radiology- implementation
of percutaneous thermal ablation as an additional therapeutic method for small renal masses.
Diagnostics (Basel). 2022;12:6.
23. Ginat DT, Saad WE. Bowel displacement and
protection techniques during percutaneous renal