Srm

Evaluation and Management of
Small Renal Mass

INTRODUCTION
• Renal Cell Carcinoma - 3% of all adult cancers.
• It is the most lethal of all genitourinary
malignancies - 25% mortality.
• During the last 30 years the incidence has
increased by about 3% per year, reflecting an
increase in the incidental detection of SRM with
abdominal imaging.

• The mortality rate of symptomatic and
incidental RCC is comparable.
• Long natural history and are not destined to
progress.
• Those likely to progress are probably resected
too late despite their localized radiographic
appearance.

DEFINITION
• SRM is a small (<4 cm), solid, sporadic, apparently
organ confined tumor, suspicious for RCC based on
imaging characteristics.
• Some argue that larger tumors should be included as
SRMs, based on
1. pathological tumor size is about 1.0 cm less than
radiographic tumor size, and
2. excellent oncologic outcomes have been reported for
organ confined tumors as large as 7 cm.

• Large surgical series indicate that
approximately 20% of neoplasms removed as
suspected renal cancers are benign on final
pathology and only 20% are potentially
aggressive RCCs, as defined by high nuclear
grade or presence of locally invasive features.
• Histologic subtyping is critical to
understanding natural history of disease.

ONCOCYTOMA
• Benign kidney tumor
characterized by cells with
eosinophilic granular
cytoplasm and low grade
nuclei growing in nests.
• Cytogenetics: alterations in
chr 11q,13.
• Classically described as
"mahogany brown with
central stellate scar”.
• Electron microscopy:
Cytoplasm filled with
abundant mitochondria.

• Renal oncocytoma is the most common
benign tumor that appears as an enhancing
renal mass on cross-sectional imaging and is
presumed to be RCC until surgical excision,
representing one of the ultimate challenges in
preoperative diagnosis for the urologist.
• It accounts for 3% to 7% of kidney tumors

• The chromosomal abnormalities typically seen
in RCC are not seen in renal oncocytomas,
further reinforcing the concept that these
tumors are genotypically distinct from RCC
(Herbers et al, 1998; Minor et al, 2003).
• However, histologically, the greatest dilemma
arises from distinguishing chromophobe and
clear cell RCC with eosinophilic characteristics
from oncocytomas

• The diagnostic accuracy of percutaneous
biopsy has markedly improved, particularly
when a core biopsy is done in addition to a
fine-needle aspiration and is bolstered with
the use of immunostains prompting some
investigators to revisit the role of the biopsy in
the management of some patients with an
incidental renal tumor

• If oncocytoma is suspected preoperatively, a
percutaneous core biopsy in addition to fine-
needle aspiration may reliably provide a
diagnosis when core tissue is available for
additional immunohistochemical studies.

• If oncocytoma is highly suspected and surgery is
indicated, a nephronsparing approach is
preferred, given the benign nature of these
lesions and the very low probability of
recurrence.
• Frozen section analysis is usually not sensitive
enough to differentiate the eosinophilic
appearance of oncocytomas from eosinophilic
RCC and should not be used to guide surgical
strategy

Angiomyolipoma
• Benign tumor composed of fat, smooth muscle cells and
thick-walled vessels; believe to originate from
perivascular epithelioid cells (PEC) (aka, PEComa).
• May arise in association with tuberous sclerosis:
1. >50% of patients with TS develop AMLs; <50% of AML
has TS
2. Tend to be asymptomatic, bilateral, small, and multiple.
• Abundant fat containing tumor recognizable
radiologically.

• Angiomyolipoma accounts for less than 10%
of renal tumors, with autopsy series and
ultrasound-screened populations showing
incidences of 0.3% and 0.13%, respectively, in
the general population
• Angiomyolipoma is the most common renal
neoplasm associated with spontaneous
perirenal hemorrhage, closely followed by RCC

• Angiomyolipoma is the only benign renal
tumor that is confidently diagnosed on cross-
sectional imaging
• The presence of fat (confirmed on
nonenhanced thin-cut CT by a value of −20 HU
or less) within a renal lesion is considered the
diagnostic hallmark

• Despite the radiographic hallmarks of
angiomyolipoma, the diagnosis can be difficult to
make in the three following situations: confusion
with liposarcoma, possibility of fat-containing
RCC, and possibility of a fat-poor angiomyolipoma
resembling an RCC.
• Although RCC containing fat density has also
been reported, these extremely rare cases also
contained calcifications, a finding almost never
seen with angiomyolipoma

• Because of the nonspecific nature of these
findings most patients are often treated as having
a presumed RCC.
• However, these radiographic findings may prompt
the attentive urologist to consider a
percutaneous biopsy if the suspicion is raised by
imaging.
• Percutaneous biopsy can play an important role
in diagnosis in these patients because a core
biopsy should be eminently accurate in the
diagnosis of angiomyolipoma

• Positive immunoreactivity for HMB-45 (human
melanoma black 45), a monoclonal antibody
raised against a melanoma-associated antigen,
is characteristic for angiomyolipoma and can
be used to differentiate this tumor from
sarcoma and other tumors

• Intervention should be considered for larger tumors,
particularly if the patient is symptomatic, taking into
account the patient’s age, comorbidities, and other
related factors.
• The treatment of choice in patients with acute
hemorrhage is selective renal angioembolization.
• Treatment options for elective management of larger
angiomyolipomas include selective renal
angioembolization and open or minimally invasive
partial nephrectomy.
• Embolization is associated with a high rate of
secondary procedures

PAPILLARY ADENOMA
• Small epithelial tumor with papillary and/or tubular
growth that is not >0.5 cm in size (those larger
becomes papillary RCC, usually type 1).
• Seen in 7% of nephrectomies and higher in chronic
renal disease with acquired cystic disease (~35%).
• The incidence of papillary adenomas increases with
age (40% of patients over 70 years of age in autopsy
studies) and male sex, and these tumors also have
been associated with acquired renal cystic disease that
results in end-stage renal failure

• To be considered papillary
adenomas, these lesions
should histologically be 5 mm
or smaller; well circumscribed;
characterized by uniform
basophilic or eosinophilic cells
with benign-appearing nuclear
and cellular features; and
arranged in papillary, tubular,
or tubulopapillary
architecture; and they should
not resemble clear cell,
chromophobe, or collecting
duct RCC (Grignon and Eble,
1998).

• In fact, in a more recent study in which
immunohistochemical analyses were used to
further characterize renal adenomas, it was
suggested that these lesions may be linked to
the development of papillary RCC and
represent a biologic link and continuum as a
premalignant precursor (Wang et al, 2007).

• The diagnosis of papillary adenoma remains
controversial; many believe that all solid renal
epithelium-derived masses are potentially
malignant and therefore should undergo
treatment (Renshaw, 2002).

Metanephric Adenoma
• Benign neoplasm
composed of small
primitive cells or small
blue cells that look like
immature metanephric
tubules.
• Tumor suppressor gene
located on chr 2p13.
• Wide age range (11
months to 83 years old;
mean 41 years).
Female>male.

• Metanephric adenoma is a recently described,
rare, benign mass that radiographically may
be indistinguishable from RCC.
• The diagnosis is often made after surgical
excision and can be confirmed with
immunohistochemical panels for cytokeratins,
WT1, S-100, and AMACR and by checking for
BRAF V600E mutations.

• Given the rarity of this tumor and the lack of
highly predictive clinical or radiographic criteria,
metanephric adenoma remains primarily a
pathologic diagnosis.
• If radiographic findings raise the index of
suspicion, then percutaneous core biopsy with
fine needle aspiration may prove helpful in
establishing a diagnosis for nephron-sparing
treatment or observation, but most patients will
require surgical excision because of concern for
malignancy

• Only one case of metastasis has been
described in association with classic
metanephric adenoma into a regional lymph
node, and death related to this entity has not
been reported (Drut et al, 2001).

Leiomyoma
• Leiomyomas are rare, benign tumors that may
arise from smooth muscle cells anywhere along
the genitourinary tract
• In the kidney these tumors most commonly arise
from the renal capsule, but renal pelvis and renal
vein sites of origin have been reported
• Leiomyomas are found at autopsy with a
frequency of 4.2% to 5.2%, but only a minority
are discovered clinically, representing
approximately 1.5% of all benign renal tumors
treated surgically

• Renal leiomyomas have
a characteristic
appearance of a small
exophytic renal mass
with or without
enhancement arising
from renal capsule, but
conclusive radiologic
differentiation from RCC
is not possible

• Malignant tumors sub-classified into:
– conventional RCC
– papillary RCC
– chromophobe RCC
– collecting duct carcinoma
– medullary carcinoma
– unclassifiable

Clear Cell Renal Cell Carcinoma
• Most common type of RCC.
• Almost all von Hippel-Lindau syndrome patients
will develop clear cell RCC.
• Mostly asymptomatic; classic triad of abdominal
mass, flank pain and hematuria detected in only
~1/3 of patients.
• Nuclear grading based on Fuhrman classification
(grades 1-4).

Clear Cell Renal Cell Carcinoma

Papillary Renal Cell Carcinoma
• 2nd most common type
of renal carcinoma,
divided into 2 types
(types 1 or basophilic and
2 or eosinophilic).
• Has higher tendency for
multifocality and
bilaterality than other
RCC.
• Behavior is better than
clear cell RCC but worse
than chromophobe RCC.

Chromophobe Renal Cell Carcinoma
• 3rd most common
subtype of RCC.
• Morphologically has
"classic" and eosinophilic
types, the later has
significant overlap with
oncocytoma and often
poses a diagnostic
problem.
• Better survival than clear
cell and papillary RCCs (5
year survival of >90%).

Collecting Duct Carcinoma
• High-grade
adenocarcinoma arising
from collecting duct
epithelial cells.
• Aggressive, frequently
presents with higher
stage or metastasis.
• 50% of patients die of
disease in 2 years.

Renal Medullary Carcinoma
• Highly aggressive renal
neoplasm that has
association with sickle
cell trait.
• Usually encountered in
young patients, male >
female (2:1), mostly
African-American and
with sickle cell
hemoglobinopathies.

Renal Tumors in Familial Syndromes
• Von Hippel-Lindau Syndrome
• Tumor type: clear cell RCC, and normal kidney
parenchyma contains multiple small "clear cell RCC"
tumorlets as minute nests and cysts.
• Other manifestations: hemangioblastoma, pancreatic
tumor or cyst, pheochromocytoma, endolymphatic sac
tumors and epididymal cystadenoma.
• Inheritance: autosomal dominant.
• Gene: (VHL tumor suppressor gene).

Birt-Hogg-Dubé Syndrome
• Tumor type: chromophobe RCC/renal
oncocytoma with overlapping features of these 2
tumors.
• Other manifestations: cutaneous lesions
(fibrofolliculomas, trichodiscoma) and pulmonary
cysts (may have spontaneous hemothorax).
• Gene: BHD gene encodes folliculin

Hereditary Papillary Renal Cell
Carcinoma
• Tumor type: papillary RCC type 1, multiple
and bilateral.
• Inheritance: autosomal dominant
• Gene: c-met oncogene.

Hereditary Leiomyomatosis and Renal
Cell Cancer Syndrome
• Tumor type: papillary RCC type 2 and collecting
duct carcinoma (tumor cells characterized by
large central nucleolus surrounded by halo or
"CMV-like" inclusion).
• Other manifestations: leiomyoma of skin and
uterus.
• Gene: fumarate hydratase gene.

Lymphoma
• Primary renal lymphoma is rare.
• Kidney is often involved secondarily by
systemic lymphoma, especially non-Hodgkin's
lymphomas with extensive retroperitoneal
disease.
• The most common primary renal lymphoma is
post-transplant lymphoproliferative disorder.

Renal Sarcomas
• Renal sarcomas arising primarily within the
kidney are very rare.
• Most renal sarcomas are secondary involvement
from a retroperitoneal origin.
• Most common is leiomyosarcoma, which may
arise from the renal veins and its branches.
Other sarcomas include Synovial sarcoma,
Primitive neuroectodermal tumor,
Angiosarcoma, Liposarcoma.

Secondary Tumors
• Metastasis
• Present as multifocal and bilateral, but may
present as solitary tumor mimicking primary
tumor Lung carcinomas, the most frequent
source of metastatic carcinoma.
• Other common primaries: contralateral kidney,
breast and GI tract.
• Morphology, most common is adenocarcinoma
followed by squamous cell carcinoma and small
cell carcinoma.

Tumour Size
• A strong indicator of malignancy is tumor size,
which directly correlates with risk of malignancy.
• Data from the Mayo Clinic indicate that the
percentage of benign tumors decreased from
46% for those <1 cm to 6.3% for those >7 cm.
• In series from Memorial Sloan-Kettering Cancer
Center each 1 cm increase in tumor size was
associated with a 16% increase in the odds of
malignancy such that 22% of all tumors <4 cm
are benign.

DIAGNOSIS AND EVALUATION
• SRMs detected with USG or IVP should be further
investigated using CT before and after i.v contrast
administration, presuming adequate renal
function.
• A 3-phase study, including non-contrast, early
vascular and delayed excretory phases, is
preferred as enhancement is often best
appreciated on the delayed images.
• MRI may be reserved for patients with moderate
renal dysfunction or allergy to intravenous
contrast material.

• Any renal neoplasm that demonstrates enhancement
on CT or MRI and does not demonstrate fat (HU <-20)
has generally been considered a malignant neoplasm
until pathological analysis proves otherwise.
• Although RCC is by far the most common diagnosis, no
clinical or radiographic feature can predict the
presence of malignancy with sufficient accuracy to
exclude benign lesions.
• Prediction of potentially aggressive histology, cannot
be reliably made based on clinical or radiographic
features alone.

• Molecular imaging using a radiolabeled antibody
to a marker expressed by the most common RCC
subtype, clear cell RCC, has been used to
differentiate this more aggressive subtype from
the other indolent or benign renal cortical
tumors.
• In the initial clinical trial of PET scan for detection
of 124 iodine labeled antibody to carbonic
anhydrase, sensitivity was 94% and specificity
was 100% for identification of clear cell RCC.

ROLE OF RENAL MASS BIOPSY
• RMB was abandoned in the past due to concerns
about false-negative results and fear of
complications.
• The diagnostic accuracy of RMB in studies before
2001 averaged 82%, but has increased to 90% in
studies since 2001.
• In addition, the majority of these procedures can
be performed in the outpatient setting under
radiographic (ultrasound, CT, MRI) guidance with
minimal morbidity.

• Fewer than 1% of patients experience
bleeding leading to clinical intervention or
hospitalization.
• Needle tract seeding, which is a major
concern with infiltrative renal masses such as
high grade urothelial carcinoma, is rare with
well circumscribed SRMs.

Biopsy_Traditional indications
• SRMs that are indeterminate on abdominal
imaging
• Possibility of lymphoma
• Renal abscess
• Renal masses that are suspicious for metastatic
disease in the presence of a known extra-renal
malignancy
• Unresectable retroperitoneal tumors involving
the kidney

Biopsy_recent modifications
• High suspicion for benign disease
– Young women with solid tumor – AML?
• Suspect tumor of low metastatic potential
– Chromophobe RCC
– Papillary RCC, Type 1
• Poor surgical risk
• High risk of chronic kidney disease

Newer studies_ good results
• Diagnostic yeild_ 78 to 100%
• Sensitivity_ 92.1%
• Specificity for malignancy_ 89.7%
• Accuracy for Fuhrmann grade_ 63-76%
• Accuracy for subtype_ 86-98%

Conclusion
• RMB should be considered as many patients
will be treated too aggressively and some
perhaps too conservatively.
• However, healthy patients who are unwilling
to accept the uncertainty associated with RMB
and older patients who will be treated
conservatively with AS do not need RMB.

TREATMENT OPTIONS
• Radical nephrectomy
• Partial nephrectomy
• Thermal ablation/Cryablation
• Active surveillance

Radical nephrectomy
• RN, even when adrenalectomy and lymphadenectomy
are excluded, represents therapeutic overkill for most
patients with an SRM, and should only be performed
when the involved kidney has poor function or when
truly necessary, based on hilar location.
• RN has a significant negative impact on renal function
and contributes to the development of chronic kidney
disease.
• The main concern with RN is that it predisposes to CKD,
which is potentially associated with morbid
cardiovascular events and increased mortality rates.

Laparoscopic radical nephrectomy
• Laparoscopic radical nephrectomy, first described in
1991, has provided a less invasive approach and served
as the backbone for subsequent minimally invasive
treatments for SRMs.
• LRN offers several short-term advantages over ORN in
terms of morbidity and convalescence, and appears to
have comparable oncologic outcomes for localized
RCC.
• Concern regarding LRN is its widespread use for SRMs,
many of which might be amenable to a nephron-
sparing approach that would permit greater
preservation of renal function.

Partial nephrectomy
• PN, in which the uninvolved portion of the kidney
is preserved after removal of the tumor with a
small rim of normal parenchyma, was initially
attempted in patients in whom RN would render
them dependent on renal replacement therapy.
• PN is associated with oncologic outcomes
comparable to those of RN.
• Recent evidence suggests that patients
undergoing PN survive longer than those
undergoing RN.

Open partial nephrectomy
• Open partial nephrectomy has the longest and most
robust data regarding oncologic and renal function
outcomes.
• Long-term cancer specific survival exceeds 90% for
patients undergoing elective OPN for SRMs,
representing a gold standard in the field.
• Tumor excision is generally performed after temporary
occlusion of the renal vasculature.
• Resection without ischemia has also been advocated
but can be associated with decreased visibility due to
parenchymal bleeding.

• The duration of the ischemic interval is the most
important modifiable risk factor for the
development of CKD after PN.
• The ability to perform OPN with regional
hypothermia (cold ischemia) may provide a renal
functional advantage over techniques using warm
ischemia.
• OPN remains the treatment of choice for patients
with SRMs, moderate to severe CKD and/ or a
solitary kidney in whom the margin for error is
small.

Laparoscopic partial nephrectomy
• In a comparative analysis of OPN and LPN
performed at 3 large referral centers LPN was
associated with less intraoperative blood loss
and shorter hospital stays but longer warm
ischemic times and higher risk of
complications, including postoperative
hemorrhage and urinary leak.

• Various hemostatic agents and devices have
been proposed to reduce the incidence of
postoperative bleeding, and on-demand
clamping and early unclamping have been used
to reduce the duration of warm ischemia.
• Minimally invasive PN is now well established for
exophytic and partially endophytic tumors, and
encouraging results with LPN and robot assisted
LPN have been reported for more challenging
tumors, including SRMs that abut the renal hilum.

Complications- Nephron Sparing Surgery
Variable Partial Nephrectomy Approach
Mean % (range) Laparoscopic Laparoscopic-RP Robotic Open
N 11505 255 1055 9947
Acute Kidney Injury 0.7 (0.6-0.9) Not reported 0 3.5 (0.5-13)
Death 0.3* Not reported 0 0.5*
Nephrectomy 1.8 (0.5-4) Not reported 3.6 (1.6-7.7) 0
Clavien 3+ 11 (0-36) 4.5* 4.9 (0-8.2) 5 (4-6.7)
Embolization 1.7 (0.5-4) 0.9* 1.7 (1-2.6) 3*
Urine leak 3.4 (1-8) 0-1.8 3.9 (1-16.8)** 2.5 (0.6-5.5)
Blood transfusion 6.3 (1.6-12.5) 2.7-5.1 4.2 (0-7.1) 8.2 (5.1-11)
Readmission 11 (10.4-11.1)* Not reported 11.9* Not reported

Partial Vs Radical
• A prospective trial of RN versus PN was reported
in 2011 that has stimulated great controversy.
• EORTC 30904, randomized over 500 patients with
small (<5.0-cm) unifocal tumors and a normal
contralateral kidney to RN versus elective PN, and
showed an advantage for RN in terms of lower
perioperative morbidity, while PN provided better
renal functional outcomes

• 10-year overall survival was in reality better for RN
than PN (81% vs. 76%, respectively, P < .05), and
cardiovascular deaths were less common in the RN
group.
• This trial has some flaws and most thought leaders in
the field, including the authors, do not choose to
interpret it literally.
• However, EORTC 30904 has stimulated further research
by suggesting that the functional advantage of PN in
the setting of a normal contralateral kidney may not be
as beneficial as previously believed.

Conclusions from various trials
• PN is preferred for small renal masses (T1a, <4.0
cm) whenever feasible, because RN represents
gross overtreatment for most such lesions, which
tend to have limited biologic potential.
• PN is also strongly preferred whenever
preservation of renal function is potentially
important, such as patients with preexisting CKD,
those with an abnormal contralateral kidney, or
those with multifocal or familial RCC.

• Larger renal tumors (clinical stages T1b and T2)
have increased oncologic potential and have
often already replaced a substantial portion of
the parenchyma, leaving less to be saved by PN.
In the setting of a normal contralateral kidney,
the relative merits of PN versus RN can be
debated in this population.
• Well-designed randomized, prospective trials will
be required to provide higher quality data and to
allow for more rational management of patients
with localized renal tumors.

Surveillance after Radical or Partial
Nephrectomy*

Thermal ablation
• TA, including cryoablation and radio frequency
ablation, has emerged as an alternative
nephron sparing treatment for SRMs.
• The long-term efficacy of TA has not been
established and available date suggest that
the local recurrence rates may be higher than
those reported for PN and RN.

Indications
1. patients of advanced age,
2. those with significant comorbidities who prefer
a proactive approach but are not optimal
candidates to undergo conventional surgery,
3. patients with local recurrence after previous
nephron-sparing surgery and
4. those with multifocal tumors.

Advantages
• Nephron-sparing
• Low morbidity
• Fewer complications
• Outpatient
• Ease of radiographic follow up

Cryoablation
• Cryoablation probes capitalize on the Joule-
Thomson effect by using pressurized argon and
helium gases to rapidly freeze and thaw targeted
lesions.
• Extracellular freezing, targeted tissue desiccation,
intracellular pH alterations, and protein
denaturation can occur during active cooling.
• Intracellular ice crystal formation accounts for the
mechanical destruction of the intracellular
organelles as well the cell membrane when
temperatures approach a tumoricidal −40 oC.

Normal renal tissue
(- 19.4 °C)
Renal tumour
(- 40 °C)

• A slow thaw is important for the recrystallization
process because the intracellular ice crystal
continues to expand.
• Repeated cycles improve the odds of the
complete eradication of the tumor.
• Once cryoablation is complete, reperfusion of the
damaged microcirculation leads to microthrombi
formation and microcirculatory occlusion, thus
resulting in tissue ischemia and destruction.

Laparoscopic Cryoablation
Transperitoneal
- anterior renal mass
Retroperitoneal
- posterior renal mass

Percutaneous Cryoablation
MRI guided CT guided

Follow-up and Recurrence
• Central or nodular enhancement within the
tumor bed on extended followup has been
considered diagnostic of local recurrence.
• Most local recurrences can be salvaged with
repeat ablation but, some patients with
progressive disease eventually require
conventional surgery.
• Nguyen and Campbell reported that surgery is
often not possible in this setting due to the
extensive fibrotic reaction induced by previous
treatment.

Results
• The results of cryoablation for 5 and 10-year
disease free survival rates were 78% and 51%,
respectively, which is much less than would be
expected for PN for an analogous population
of patients with SRMs.

Radio Frequency Ablation
• RFA uses alternating radiofrequency energy delivered
by a probe, generating heat from the impedance of
targeted cells to achieve cell death and coagulation
necrosis.
• Temperatures can reach up to 105 oC, but tissue is
destroyed at temperatures exceeding 70 oC, leaving
behind a necrotic lesion after 24 to 48 hours and
reaching maximal size within 7 days.
• A disadvantage of RFA is that the treatment effect is
difficult to monitor in real time as there is no true ice
ball equivalent and local control is difficult to
determine.

Approaches
• Laparoscopic Radiofrency Ablation
• Percutaneous Radiofrequency Ablation
• MRI: currently the best
• - allows re-treatment of residual tumour in the same
session
• CT: (done under sedation)
• - limitation in the detection of residual tumour in the
same session

Pre-ablation 3 Months Post
12 Months Post
Lesion Progression:
1. Wedge/spherical
non-enhancing
2. Gradual contraction
residual scar
RFA Results

Results
• Local control is achieved in about 80% to 90% of
cases based on loss of enhancement within the
lesion on cross-sectional imaging as an indicator
of successful treatment.
• Weight et al described 6 patients with no
enhancement on MRI 6 months after RFA who
were found to have apparently viable cancer cells
on biopsy of the tumor bed, indicating that 24%
of lesions with no radiographic suspicion for
tumor persistence may have been incompletely
treated.

• For RFA, local recurrence-free outcomes range
between 88% and 92% and corresponding rates
for CA are 80% to approximately 86%. Metastasis-
free survival and CSS exceed 90% in virtually all
series.
• The AUA Guidelines Panel examined 10 studies of
CA and 10 studies of RFA and determined a local
recurrence–free survival of 90.6% (83.8% to
94.7%) for CA and 87.0% (83.2% to 90%) for RFA
(Novick et al, 2009).

• When compared to alternative extirpative
treatments, both CA and RFA demonstrated
significantly higher rates of local recurrence
despite a shorter overall duration of follow-up,
with no significant difference in local
recurrence– free survival between CA and RFA
and no difference in metastasisfree survival or
CSS between ablation and surgical excision.

Metastatic Recurrence–Free Survival
• mean metastatic recurrence–free survival was
95.3% (91.1% to 97.5%) for CA and 97.5%
(94.8% to 98.8%) for RFA (Novick et al, 2009).
• There was no significant difference in
metastatic recurrence–free survival between
tumor ablation and extirpative treatments,
including laparoscopic and open partial and
radical nephrectomy.

Cancer-Specific Survival
• The AUA meta-analysis published in 2009
evaluated the risk for dying from RCC after CA or
RFA and concluded that CSS was 95.2% (89.2% to
97.9%) with CA and 98.1% (95.2% to 99.2%) with
RFA.
• CSS was significantly higher with laparoscopic
partial nephrectomy than for CA, but there was
no significant difference in CSS between
laparoscopic partial nephrectomy and RFA.
• There also was no significant difference in CSS
between CA and RFA.

Overall Survival
• Patients undergoing ablative procedures tend to
be older and have more comorbidities than those
undergoing extirpative surgery (Novick et al,
2009).
• Thus the mean overall survival rate after ablative
procedures is typically 75% to 85% at 5 years
• There does not appear to be any significant
difference in overall survival between CA and
RFA.

COMPLICATIONS
• The incidence of major urologic complications
with renal CA and RFA was 4.9% (range 3.3%
to 7.4%) and 6.0% (4.3% to 8.2%),
respectively.
• Major nonurologic problems occurred in 5%
(3.5% to 7.2%) of patients undergoing CA and
4.5% (3.2% to 6.2%) of those undergoing RFA.

• The risk for major urologic complications was
lower with ablative techniques than with
either laparoscopic or open partial
nephrectomy.
• There was no significant difference in urologic
complications with CA versus RFA.

NEW ABLATION MODALITIES
• HIFU
• Laser Interstitial Thermal Therapy
• Irreversible Electroporation
• Targeted Embolization and Ablation
• Microwave Ablation

• Ultimately, the decision to treat a small renal
mass with an ablative technology should take
into account tumor-related characteristics,
patient demographics and comorbidities, and
the values and desires of the patient.

Active surveillance
• Meta-analysis of published series
of AS of SRMs has confirmed that
many of these tumors grow
relatively slowly (0.28 cm a year)
with a low risk of metastasis on
limited followup (1.2%),
suggesting that this may be a
reasonable management strategy
in carefully selected patients.
• These studies suggest that well
marginated SRMs in patients with
limited life expectancy can safely
be managed with observation
and serial renal imaging at 6 to
12-month intervals.

Limitations to AS literature
• Most AS series have included only relatively small, well
marginated and homogeneous SRMs.
• In addition, follow-up in most series is limited to 2 to 3
years, and in some cases the growth rate was
calculated backward by obtaining old films for which
the lesion of interest was either previously missed or
dismissed, introducing a strong selection bias.
• Finally, in most of these series there is a subpopulation
with rapidly growing tumors in whom salvage is
unlikely should metastases develop.

Meta-analysis of outcomes for patients with a clinical
T1 renal mass according to management

EXPECTED OUTCOMES
• Given the indolent disease course of the majority
of SRMs, oncologic outcomes are expected to be
favorable independent of treatment choice.
• The type of treatment (RN, PN, TA or AS) is not a
statistically significant predictor of overall
survival, although there was a trend towards
increased survival with PN in the subset of
patients with longest predicted life expectancy.
• The major predictors of overall survival are age
and comorbidity, and the most common cause of
death is cardiovascular.

• The impact that SRM management has on
overall survival is the net effect of the benefits
and the risks, including the psychological
impact of a cancer diagnosis, post-procedural
complications and CKD, of each form of
treatment.
• Successful management of SRMs in older
patients should not be based solely on
oncologic considerations, as most such
patients will die of competing causes.

CONCLUSIONS
• The increased use of abdominal imaging has
resulted in a stage migration for RCC.
• Not all SRMs are malignant and the majority of
those that are cancer will follow an indolent
course after local treatment.
• Renal Mass Biopsy should be selectively
considered for risk stratification and counseling
and, when combined with molecular profiling,
will likely revolutionize this field.

• Recent evidence indicates that the risks of
Radical Nephrectomy in terms of loss of renal
function may outweigh the benefit of such an
aggressive surgical approach.
• Long-term data support the oncologic efficacy
of Partial Nephrectomy, and this treatment
should be discussed with all patients with a
SRM.

• Thermal Ablation is another nephron-sparing
approach that is a vital component of
management but its limitations must be
recognized, and balanced counseling, should
be a prerequisite.
• Active Surveillance is also a reasonable option
and should be a prime consideration in
patients with limited life expectancy.

Evaluation and Diagnosis
• In patients with a solid or complex cystic renal
mass, physicians should obtain high quality,
multiphase, cross-sectional abdominal
imaging to optimally characterize and clinically
stage the renal mass. Characterization of the
renal mass should include assessment of
tumor complexity, degree of contrast
enhancement (where applicable), and
presence or absence of fat. (Clinical Principle)

• In patients with suspected renal malignancy,
physicians should obtain comprehensive
metabolic panel, complete blood count, and
urinalysis. Metastatic evaluation should include
chest imaging to evaluate for possible thoracic
metastases. (Clinical Principle)
• For patients with a solid or complex cystic renal
mass, physicians should assign CKD stage based
on GFR and degree of proteinuria. (Expert
Opinion)

Counseling
• In patients with a solid mass, a urologist should lead
the counseling process and should consider all
management strategies. A multidisciplinary team
should be included when necessary. (Expert Opinion)
• Physicians should provide counseling that includes
current perspectives about tumor biology and a
patient-specific risk assessment inclusive of sex, tumor
size/complexity, histology (when obtained), and
imaging characteristics. For cT1a tumors, the low
oncologic risk of many small renal masses should be
reviewed. (Clinical Principle)

• During counseling of patients with a solid or Bosniak
3/4 complex cystic renal mass, physicians must review
the most common and serious urologic and non-
urologic morbidities of each treatment pathway and
the importance of patient age, comorbidities/frailty,
and life expectancy. (Clinical Principle)
• Physicians should review the importance of renal
functional recovery related to renal mass management,
including the risk of progressive CKD, potential short-
or long-term need for renal replacement therapy, and
long-term overall survival considerations. (Clinical
Principle)

• Physicians should consider referral to nephrology in
patients with a high risk of CKD progression. Such
patients may include those with eGFR less than 45
ml/min/1.73m2, confirmed proteinuria, diabetics with
preexisting CKD, or whenever eGFR is expected to be
less than 30 ml/min/1.73m2after intervention. (Expert
Opinion)
• Physicians should recommend genetic counseling for
all patients ≤ 46 years of age with renal malignancy and
consider genetic counseling for patients with multifocal
or bilateral renal masses, or if personal or family
history suggests a familial renal neoplastic
syndrome. (Expert Opinion)

Renal Mass Biopsy (RMB)
• Renal mass biopsy should be considered when a
mass is suspected to be hematologic, metastatic,
inflammatory, or infectious. (Clinical Principle)
• In the setting of a solid renal mass, RMB is not
required for: 1) young or healthy patients who
are unwilling to accept the uncertainties
associated with RMB; or 2) older or frail patients
who will be managed conservatively independent
of RMB findings. (Expert Opinion)

• When considering the utility of RMB, patients
should be counseled regarding rationale,
positive and negative predictive values,
potential risks and non-diagnostic rates of
RMB. (Clinical Principle)
• For patients with a solid renal mass who elect
RMB, multiple core biopsies are preferred
over fine needle aspiration. (Moderate
Recommendation; Evidence Level: Grade C)

Partial Nephrectomy (PN) and
Nephron-Sparing Approaches
• Physicians should prioritize PN for the
management of the cT1a renal mass when
intervention is indicated. In this setting, PN
minimizes the risk of CKD or CKD progression
and is associated with favorable oncologic
outcomes, including excellent local
control. (Moderate Recommendation;
Evidence Level: Grade B)

• Physicians should prioritize nephron-sparing
approaches for patients with solid renal
masses and an anatomic or functionally
solitary kidney, bilateral tumors, known
familial RCC, preexisting CKD, or
proteinuria. (Moderate Recommendation;
Evidence Level: Grade C)

• Physicians should consider nephron-sparing
approaches for patients with solid or Bosniak
3/4 complex cystic renal masses who are
young, have multifocal masses, or
comorbidities that are likely to impact renal
function in the future, such as moderate to
severe hypertension, diabetes mellitus,
recurrent urolithiasis, or morbid
obesity. (Conditional Recommendation;

• In patients who elect PN, physicians should
prioritize preservation of renal function
through efforts to optimize nephron mass
preservation and avoidance of prolonged
warm ischemia. (Expert Opinion)

• For patients undergoing PN, negative surgical
margins should be a priority. The extent of
normal parenchyma removed should be
determined by surgeon discretion taking into
account the clinical situation, tumor
characteristics including growth pattern, and
interface with normal tissue. Tumor enucleation
should be considered in patients with familial
RCC, multifocal disease, or severe CKD to
optimize parenchymal mass preservation. (Expert
Opinion)

Radical Nephrectomy (RN)
• Physicians should consider RN for patients with a solid or
where increased oncologic potential is suggested by tumor
size, RMB, and/or imaging characteristics and in whom
active treatment is planned. (Conditional
Recommendation; Evidence Level: Grade B) In this setting,
RN is preferred if all of the following criteria are met:
• 1) high tumor complexity and PN would be challenging
even in experienced hands;
• 2) no preexisting CKD or proteinuria; and
• 3) normal contralateral kidney and new baseline eGFR will
likely be greater than 45 ml/min/1.73m2. (Expert Opinion)

Surgical Principles
• For patients who are undergoing surgical excision
of a renal mass with clinically concerning regional
lymphadenopathy, physicians should perform a
lymph node dissection for staging
purposes. (Expert Opinion)
• For patients who are undergoing surgical excision
of a renal mass, physicians should perform
adrenalectomy if imaging and/or intraoperative
findings suggest metastasis or direct invasion of
the adrenal gland. (Clinical Principle)

• In patients undergoing surgical excision of a renal
mass, a minimally invasive approach should be
considered when it would not compromise
oncologic, functional and perioperative
outcomes. (Expert Opinion)
• Pathologic evaluation of the adjacent renal
parenchyma should be performed after PN or RN
to assess for possible intrinsic renal disease,
particularly for patients with CKD or risk factors
for developing CKD. (Clinical Principle)

Thermal Ablation (TA)
• Physicians should consider thermal ablation (TA) as an
alternate approach for the management of cT1a renal
masses <3 cm in size. For patients who elect TA, a
percutaneous technique is preferred over a surgical
approach whenever feasible to minimize
morbidity. (Conditional Recommendation; Evidence
Level: Grade C)
• Both radiofrequency ablation and cryoablation are
options for patients who elect thermal
ablation. (Conditional Recommendation; Evidence
Level: Grade C)

• A renal mass biopsy should be performed prior to
ablation to provide pathologic diagnosis and
guide subsequent surveillance. (Expert Opinion)
• Counseling about thermal ablation should include
information regarding an increased likelihood of
tumor persistence or local recurrence after
primary thermal ablation relative to surgical
extirpation, which may be addressed with repeat
ablation if further intervention is elected. (Strong
Recommendation; Evidence Level: Grade B)

Active Surveillance (AS)
• For patients with small solid mass especially
those <2cm, AS is an option for initial
management. (Conditional Recommendation;
• For patients with a solid renal mass, physicians
should prioritize active surveillance/expectant
management when the anticipated risk of
intervention or competing risks of death
outweigh the potential oncologic benefits of
active treatment. (Clinical Principle

• For patients with a solid or Bosniak 3/4
complex cystic renal mass in whom the
risk/benefit analysis for treatment is equivocal
and who prefer AS, physicians should repeat
imaging in 3-6 months to assess for interval
growth and may consider RMB for additional
risk stratification. (Expert Opinion)

• For patients with a solid or Bosniak 3/4 complex
cystic renal mass in whom the anticipated
oncologic benefits of intervention outweigh the
risks of treatment and competing risks of death,
physicians should recommend active treatment.
In this setting, AS with potential for delayed
intervention may be pursued only if the patient
understands and is willing to accept the
associated oncologic risk. (Moderate
Recommendation; Evidence Level: Grade C)

• Recommendation 1.0: On the basis of tumor-
specific findings and competing risks of
mortality, all patients with an SRM should be
considered for RTB when the results may alter
management
• (type: evidence based; evidence quality:
intermediate; strength of recommendation:
strong).

• Recommendation 2.0: Active surveillance should be an
initial management option for patients who have
significant comorbidities and limited life expectancy
• (type: evidence based; evidence quality: intermediate;
strength of recommendation: moderate).
• Qualifying statement: absolute indication: high risk for
anesthesia and intervention or life expectancy < 5
years; relative indication: significant risk of end-stage
renal disease if treated, SRM (,<1 cm), or life
expectancy <10 years.

• Recommendation 3.1: Partial nephrectomy
(PN) for SRMs is the standard treatment that
should be offered to all patients for whom an
intervention is indicated and who possess a
tumor that is amenable to this approach
(type: evidence based; evidence quality:
strong).

• Recommendation 3.2: Percutaneous thermal
ablation should be considered an option for
patients who possess tumors such that
complete ablation will be achieved. A biopsy
should be obtained before or at the time of
ablation
moderate).

• Recommendation 3.3: Radical nephrectomy for
SRMs should be reserved only for patients who
possess a tumor of significant complexity that is
not amenable to PN or where PN may result in
unacceptable morbidity even when performed at
centers with expertise. Referral to a surgeon and
a center with experience in PN should be
considered
strong).

• Recommendation 3.4: Referral to a
nephrologist should be considered if CKD
(estimated glomerular filtration rate < 45
mL/min/1.73m2) or progressive CKD develops
after treatment, especially if associated with
proteinuria
moderate). (continued on following page)

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