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Page 2 of 11 Sawada et al. Mini-invasive Surg 2021;5:6 I http://dx.doi.org/10.20517/2574-1225.2020.100

Conclusion: In selected cases, RAPN with warm ischemia appears to preserve renal function equally well or better
compared to OPN with cold ischemia.

Keywords: Partial nephrectomy, robot-assisted nephrectomy, open surgery, perioperative outcomes, renal
function, propensity score matching

INTRODUCTION
Partial nephrectomy (PN) for localized renal cell carcinoma has been reported to have oncological
outcomes equivalent to those achieved by radical nephrectomy, with preservation of postoperative renal
[1,2]
function . As a result, PN has become the standard treatment for small renal cell carcinomas.
Robot-assisted partial nephrectomy (RAPN) is recognized as a minimally invasive surgical method. Its
[3,4]
application as an alternative to open partial nephrectomy (OPN) is rapidly growing . This is largely due to
RAPN’s high-definition 3D optical system and flexible wristed instruments that allow surgeons to perform
[5]
tumor excision and renorrhaphy with an accuracy equal to or greater than that achieved by OPN .
Various studies have compared RAPN and OPN [6-12] . However, because the outcomes of PN are influenced
by several factors, including tumor location, anatomical complexity, patient renal function, and operator
proficiency, there is some controversy over which surgical approach is superior. Current guidelines do not
indicate a preference for one technique over the other, leading to decisions being predominantly made on
[13]
the basis of the surgeons’ expertise and skills .
The present study aimed to comprehensively compare the perioperative outcomes of RAPN and OPN
performed at a single institution after adjusting for preoperative patient and tumor characteristics using
propensity score matching (PSM).

METHODS
Study population
This study was approved by the Ethics Committee of Kyoto University Graduate School and Faculty of
Medicine (R1581).

We retrospectively collected clinical data of 202 patients with renal masses of cT1-2 cN0 cM0 diagnosed via
CT or MRI who underwent RAPN or OPN between 2005 and 2020 at Kyoto University Hospital. During
this period, RAPN was performed by 10 experienced surgeons and OPN was performed by 15 experienced
surgeons. The choice of the surgical method (RAPN or OPN) was determined on a case-by-case basis at
a preoperative medical conference. However, due to insurance coverage changes that came into effect in
2016, RAPN became the preferred technique. As a general rule, OPN has been applied to patients with
a single kidney or chronic kidney disease (CKD) grade 4 or higher (eGFR < 30) since 2016. Cases where
preoperative imaging was not available were excluded from the study because the anatomic complexity
of the tumors could not be accurately determined. Cases with multiple tumors were also excluded for
the same reason. Cases in which other surgeries were simultaneously conducted with PN were excluded
because perioperative outcomes of PN surgery could not be accurately evaluated.

Surgical technique
The surgeons at our hospital have received adequate surgical training, have performed many operations at
our hospital and other institutions, and are qualified practitioners in Japan. The RAPN procedure employed
at our hospital was relatively similar to that reported by Kaouk et al. and was performed using the da
[14]