The Benefit of Laparoscopic Partial Nephrectomy in High Body
Mass Index Patients
Gou Kaneko, Akira Miyajima*, Eiji Kikuchi, Ken Nakagawa and Mototsugu Oya
Department of Urology, Keio University School of Medicine, Tokyo, Japan
*For reprints and all correspondence: Akira Miyajima, Department of Urology, Keio University School of Medicine,
35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan. E-mail: email@example.com
Received December 8, 2011; accepted April 1, 2012
Objective: The aims of the present study were to evaluate the effect of body mass index on
the surgical outcomes of open partial nephrectomy and laparoscopic partial nephrectomy,
and to analyze whether higher body mass index patients may derive greater benefit from lap-
aroscopic partial nephrectomy.
Methods: We reviewed 110 patients who underwent open partial nephrectomy and 47
patients who underwent laparoscopic partial nephrectomy at our institution. We analyzed the
data to determine what kind of factor would be associated with prolonged operative time,
increased estimated blood loss and prolonged ischemic time, and compared the result
of open partial nephrectomy with that of laparoscopic partial nephrectomy.
Results: A statistically significant correlation was observed between body mass index and
operative time or estimated blood loss in open partial nephrectomy. Multivariate analysis also
demonstrated that body mass index was an independent predictor for prolonged operative
time and higher estimated blood loss in open partial nephrectomy, but not in laparoscopic
partial nephrectomy. In the normal body mass index group (body mass index , 25.0 kg/m2),
although mean operative time in the laparoscopic partial nephrectomy group was significantly
longer than that in the open partial nephrectomy group, the difference was relatively small. In
the high body mass index group (body mass index ? 25.0 kg/m2), the mean operative time of
the two groups was not statistically different. The estimated blood loss of open partial neph-
rectomy was significantly higher than that of laparoscopic partial nephrectomy in both groups.
In both operative procedures, tumor size was an independent predictor for prolonged ische-
mic time in multivariate analysis.
Conclusions: Body mass index was an independent predictor for prolonged operative time
and higher estimated blood loss in open partial nephrectomy but not in laparoscopic partial
nephrectomy. Laparoscopic partial nephrectomy was less influenced by body mass index and
had a greater benefit, especially in high body mass index patients.
Key words: Urologic-Surg – endourology – laparoscopy – partial nephrectomy – renal cell
carcinoma – body mass index
The prevalence of obesity has increased dramatically, and
obesity is now an important problem in many countries
because obese patients are more likely to have multiple
medical co-morbidities, including hypertension, diabetes and
coronary artery disease. Obesity is also associated with a
higher risk of developing renal cell carcinoma (RCC) (1).
In several series, the prevalence of obesity in patients
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Jpn J Clin Oncol 2012;42(7)619–624
Advance Access Publication 4 May 2012
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the surgical approach had only a small effect on renal func-
tion. A similar result was obtained in the present study. The
ischemic time in LPN was significantly longer than that in
OPN; however, the eGFR reduction from preoperation to 3
POM was similar. The difference in the surgical procedure
did not reduce renal function.
There are several limitations in the present study. First, al-
though the LPNs were performed by only two highly experi-
enced laparoscopic surgeons, the OPNs were performed by
many different surgeons. As described above, LPN is a tech-
nically difficult procedure because an advanced laparoscopic
technique such as intracorporeal suturing is required, and it
was reported that the intraoperative ischemic time is general-
ly longer during LPN than OPN (16), and LPN has a higher
complication rate compared with OPN (17,18). Thus, OPN
continues to be a standard procedure for small localized
renal masses, while LPN is established as an option for only
experienced surgeons at high-volume centers in both
American Urological Association and European Association
of Urology guidelines (17,18). Therefore, LPN will be per-
formed by experts only for the time being. Meanwhile, al-
though the OPNs were performed by many surgeons, all
surgeons received similar training for laparotomies, includ-
ing a partial nephrectomy, and have gained adequate experi-
ence. Therefore, it is thought that the likelihood of a
difference in surgical outcome due to the different surgeons
was relatively small. For these reasons, we believe that the
conclusion of the present study is universally applicable.
Secondly, a few patients in the present study were classified
as obese (BMI ? 30 kg/m2) according to the WHO classifi-
cation. Therefore, whether or not the present conclusion is
applicable to the group including many obese patients is still
not clear and needs to be determined in future studies.
However, the aim of the present study was not to compare
the surgical outcomes between obese and non-obese patients
as in previously reported studies. The aim was to evaluate
what kind of factor is associated with surgical outcomes of
partial nephrectomy, and BMI was used in the form of a
continuous variable as one of the clinical parameters. As a
result of multiple logistic regression analysis, it was found
that BMI was an independent predictor for a prolonged OT
and higher EBL in OPN, but not in LPN. Therefore, we con-
cluded that LPN was less influenced by BMI and had a
greater benefit, especially in high BMI patients.
Conflict of interest statement
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