69 96
had
lower
preoperative
serum
creatinine
and
higher
eGFR.
Tumor
size was
slightly
larger
in
the MIPN
group.
These
findings
reflect
the
selection
of
less
healthier
patients
for
LRC
and
resection
for
patients with
larger
tumors.
3.2.
Intraoperative
outcomes
In MIPN
patients,
the median
ischemia
time
was
15 min
(interquartile range [IQR] 12–18). On the other hand, patients
treated with LRC
received double
freeze-thaw cycle: median
first cycle timewas 10 min (IQR10–15);median second cycle
time was 8 min
(IQR 6–10). Conversion
to open
surgery was
necessary
in
four
(1.9%) MIPN
and
two
(1.2%)
LRC
patients.
In
the
MIPN
group,
conversion
was
necessary
for
severe
adhesions
(
n
= 3)
and
severe hypercapnia
(
n
= 1).
In
the
LRC
group,
conversion
to
open
surgery was
because
of
hemor-
rhage
from
the
cryoablated
area
in both
cases. Multivariate
analysis
revealed
slightly
lower
estimated
blood
loss
for
the MIPN
group
compared
to
the
LRC
group. No
significant
differences
in
total
operative
time
and
intraoperative
complication
rate were
observed
( Table 2).
3.3.
Perioperative
outcomes
Postoperative complications occurred
in 42
(48%) MIPN and
46
(52%)
LRC patients. Detailed
information on
the grade of
complications
is
shown
in
Table 3 .Multivariate
analysis
revealed
that
the postoperative complication rate was
30%
lower
in
the MIPN group
than
in
the LRC group
(20% vs 28%;
adjusted difference –11%; 95% confidence
interval
[CI] –21%
to
–2%;
p
= 0.02).
The
relative
risk
for
complications
of
Clavien-Dindo grade
2 was even greater, with a
two-thirds
reduction
for
MIPN
versus
LRC
(5.8%
vs
18%;
adjusted
difference –12%, 95% CI –19%
to –4.8%;
p
= 0.001). The
length
of
in-hospital
stay was
approximately
1
d
longer
for MIPN
than
for
LRC.
There were
no
significant
differences
in
the
rate
of blood
transfusion
( Table 2 ).
3.4.
Oncologic
outcomes
In
the
MIPN
group,
all
patients
with
a
malignant
lesion
at
final
pathology
had
pT1
disease
and were
classified
as
stage
I
according
to
the
2009
TNM
classification
system.
Median
follow-up was
similar
in
the
two groups
(43 mo
for
MIPN
and
39 mo
for
LRC).
Local
recurrence was
observed
in
six MIPN
and
four
LRC
patients, while
a
new
SRM was
diagnosed
in
four
MIPN
and
six
LRC
patients.
Distant
metastases
were
observed
in
three
MIPN
patients;
no
patient
in
the
LRC
group
developed
distant metastasis.
At
5
yr,
the
disease-free
survival
rate
was
92%
and
93%
in
the MIPN
and
LRC
groups,
respectively
( Fig. 1 A). According
to
Cox
regression
analysis,
treatment
type
(MIPN
vs
LRC)
was
not
significantly
associated with
disease-free
survival
(hazard ratio 1.06, 95% CI 0.45–2.52;
p
= 0.9). We performed
a
sensitivity analysis
for patients with a malignant
lesion at
final
pathology
and
found
similar
results
for
both
Kaplan-
Meier analysis
( Fig. 1 B) and Cox
regression analysis
(hazard
ratio
1.42,
95%
CI
0.54–3.70;
p
= 0.5).
3.5.
Functional
outcomes
The variation and percentage
reduction
in eGFR after surgery
are
shown
in
Figure 2 .The
MIPN
group
had
higher
preoperative eGFR
than
the LRC group. Patients
treated with
MIPN
showed
a
higher
percentage
decrease
in
eGFR
in
the
first
6 mo
after
surgery,
as well
as
good
recovery
of
renal
function
in
the
following
2
yr,
reaching
a
plateau
approxi-
mately 3 yr after surgery. Patients treatedwith LRC showed a
similar percentage decrease
in eGFR on postoperative day 1,
followed
by
a
gradual
and
constant
percentage
reduction
over
time
( Fig. 2B).
In multivariate
linear regression analysis,
LRC was
significantly
associated with
higher
eGFR
at
6 mo
compared
to
MIPN
(coefficient
4.68,
95%
CI
0.06–9.30;
p
= 0.047) after adjusting
for preoperative eGFR, patient age,
and
tumor
dimension.
However,
there
was
no
significant
Table
2
–
Intraoperative
and
postoperative
outcomes
of MIPN
compared
to
LRC
after
adjusting
for
age, ASA
score,
and
tumor
dimension
Outcome
MIPN
(
n
= 206)
LRC
(
n
= 166)
Adjusted
difference
95%
CI
p
value
Mean
blood
loss
(ml)
135
(131)
192
(338)
–73 ml
–127
to
–20 ml
0.007
Mean
operative
time
(min)
187
(63)
188
(66)
–13 min
–27
to
1 min
0.074
Intraoperative
complications
a10
(4.9)
9
(5.4)
0%
–4%
to
4%
0.9
Blood
transfusions
a10
(4.9)
16
(10)
–3.7%
–9.2%
to
1.2%
0.2
Postoperative
complications
42
(20)
46
(28)
–11%
–21%
to
1.5%
0.02
Clavien
complication
grade
2
a12
(5.8)
30
(18)
–12%
–19%
to
–4.8%
0.001
Mean
length
of
stay
(d)
6
(2)
5
(2)
1
0.5–1.5
d
<
0.0001
MIPN = minimally
invasive
partial
nephrectomy;
LRC =
laparoscopic
renal
cryoablation; ASA = American
Society
of Anesthesiologists;
CI =
confidence
interval.
Continuous
data
are
presented
as mean
(standard
deviation)
and
categorical
data
as
n
(%).
a
Data were
adjusted
only
for
ASA
score
because
of
the
low
number
of
events
observed.
Table 3 – Grade of postoperative complications
for MIPN compared
to
LRC
Complications
Patients,
n
(%)
MIPN
LRC
No
complication
164
(80)
120
(72)
Clavien
grade
I
30
(14)
16
(10)
Clavien
grade
II
9
(4.5)
25
(15)
Clavien
grade
III
3
(1.5)
2
(1.2)
Clavien
grade
IV
0
(0)
3
(1.8)
MIPN = minimally
invasive
partial
nephrectomy;
LRC =
laparoscopic
renal
cryoablation.
E U R O P E A N
U R O L O G Y
F O C U S
1
( 2 0 1 5
)
6 6 – 7 2
69