71 96
patients
in
the
LRC
group
(20%)
than
in
the
partial
nephrectomy
group
(5%).
Even
though
the
authors
did
not document
the
specific
causes
of
the
solitary
kidneys,
it
could
be
argued
that
previous
renal
tumors
treated with
radical
nephrectomy
represent
one
of
the
main
reasons.
Therefore,
this difference could have an
important effect on
oncologic outcomes. Similarly,
in studies by Haber et al
[26]and
Aron
et
al
[16],
the
proportion
of
patients
with
a
previous
history
of
renal
surgery
in
the
ipsilateral
kidney
was
dramatically
higher
in
the
LRC
group
(17%
and
27%)
than
in
the partial nephrectomy group
(0%
in both
studies).
Previous history of RCC
is an
important predictor of adverse
oncologic
outcomes
[16],
so
such
studies
are
prone
to
selection
bias. By
contrast,
the
current
study
included
only
patients diagnosed with
a
first
episode of
a
single
SRM
and
showed
comparable
oncologic
outcomes
between
MIPN
and
LRC.
Second,
to
the
best
of
our
knowledge
this
is
the
first
study
to
compare
functional
outcomes
of MIPN
and
LRC
in
patients
without
a
previous
history
of
renal
surgery,
evaluating
the variations of eGFR
levels over
time. Although
the
two
techniques provided similar
functional outcomes at
3 yr, as expected, MIPNwas associated with a
large decrease
in
eGFR
in
the
first
few
months
after
surgery
and
with
recovery
of
renal
function
in
the
next
2
yr.
Therefore,
although
renal
function
was
similar
several
years
after
treatment,
clamping
of
the
renal
vessels
during
partial
nephrectomy could
lead
to a
significant decrease
in eGFR
in
the
early
postoperative
period,
especially
in
patients with
moderate
or
severe
chronic
kidney
disease.
Third,
LRC
was
associated
with
a
higher
complication
rate and higher
complication grade, with a
threefold higher
risk of Clavien-Dindo grade
2. This
finding
is
in contrast
to
previous
reports
of
a
lower
complication
rate
in
patients
treated with
LRC
[11,27]. However,
this
disparity
seems
to
be
related
to
fewer
complications
in
the MIPN group
rather
than more
complications
in
the LRC group. Guillotreau et al
[13]observed major complication
rates
(defined as Clavien-
Dindo
3) of 3.5% and 2.9%
in patients
treated with LRC and
MIPN,
respectively;
the
corresponding
rates
in
our
series
were
3.0%
and
1.5%.
This
finding
could
be
related
to
a
selection
bias,
since
treatment
choice
was
left
to
the
discretion of
the
surgeon and
challenging
cases
selected
for
nephron-sparing
surgery
were
more
likely
to
be
treated
with open partial nephrectomy
rather
than MIPN. From
this
perspective,
it
could
be
hypothesized
that
postoperative
complications
greatly
depend
on
patient
characteristics
as
well
as
tumor
complexity, while
surgical
technique plays
a
minor
role
in
postoperative
outcomes. However,
given
the
retrospective
nature
of
our
study,
we
were
unable
to
evaluate
tumor
complexity
using
modern
nephrometry
scores
such
as
the RENAL
and
PADUA
scores
[28,29]in
the
entire
population.
This
point
warrants
investigation
in
future
studies.
Finally,
in
the MIPN group, all patients with a malignant
lesion
at
final
pathology
had
pT1
disease,
and
no
pT3
disease was observed. This
finding could be strictly
related
to
patient
selection,
as
all
patients were
newly
diagnosed
with
a
single
SRM
and no patient had undergone previous
renal
surgery.
In
addition,
the MIPN
group
represents
a
highly
selected population
since
treatment
choice was
left
to
the discretion of
the
surgeon
and
challenging
cases were
more
likely
to
receive open
surgery. These
selection
criteria
could
explain
the
fact
that no pT3 disease was
observed.
Our
study
has
important
clinical
implications
for
SRM
management.
The
two
surgical
techniques
analyzed
provided
similar
oncologic
and
functional
outcomes
in
patients
newly
diagnosed
with
a
single
SRM.
Previous
studies onMIPN and LRCwere often hampered by selection
biases and a
lack of
control groups. On
the
contrary,
in
this
study we directly compared
the
two surgical
techniques
in
patients
newly
diagnosed
with
a
single
SRM.
In
this
context,
our
study
highlighted
similar
results
for
MIPN
and LRC
in terms of oncologic and
functional outcomes. Our
findings
are
strengthened by
the
single-institution nature
of
the
study. Moreover,
the
same
surgical
techniques
for
MIPN and LRC were used
throughout
the years by different
surgeons,
all
of
whom
trained
under
the
same
master.
Despite
its strengths, our study
is not devoid of
limitations.
First,
patients
in
the
two
groups
showed
important
differences
in clinical characteristics, with
the MIPN group
including
younger
and
healthier
patients.
For
this
reason,
our
analyses were
adjusted
for patient
age
and ASA
score.
Second,
treatment
choice was
left
at
the
discretion
of
the
surgeon,
representing
a
selection
bias
for
our
study.
Moreover,
candidate
selection
for MIPN
could
represent
a
further
selection bias,
since challenging cases were more
likely
to
receive
open
surgery
rather
than
minimally
invasive
approaches.
Third,
nephrometry
scores
such
as
the
RENAL
and
PADUA
scores
[28,29]are
important
tools
for
assessing
tumor
complexity.
Given
the
retrospective
nature
of
our
study,
we
were
unable
to
retrieve
the
information
required
to
address
tumor
complexity
for
the
entire
population.
Finally,
a
low
number
of
patients
experienced
cancer
recurrence
in
both
groups.
Thus,
further
studies with
an
observational
arm
and
longer
follow-up
are
needed.
5.
Conclusions
MIPN
and
LRC
provided
similar
cancer
control
and
comparable
renal
function
at
intermediate-term
follow-
up.
In
this
single-centre
study,
both
surgical
techniques
emerged
as
viable
treatment
options
for
the management
of
patients
newly
diagnosed
with
a
single
SRM.
Further
multi-institutional
studies
with
longer
follow-up
and
nephrometry
scores
are
needed
to
corroborate
our
find-
ings.
Author
contributions:
Nicola
Fossati had
full access
to all
the data
in
the
study
and
takes
responsibility
for
the
integrity
of
the
data
and
the
accuracy
of
the
data
analysis.
Study
concept
and
design:
Fossati,
Buffi.
Acquisition
of
data:
Carenzi, Gadda, Mistretta.
Analysis
and
interpretation
of
data:
Fossati,
Larcher,
Lughezzani.
Drafting
of
the manuscript:
Fossati,
Larcher.
Critical
revision
of
the
manuscript
for
important
intellectual
content:
Vickers,
Lazzeri,
Lista, Dell’Oglio, Montorsi, Guazzoni.
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