Original Article

Yonago Acta medica 2016;59:135–142

The First Pilot Comprehensive Evaluation of the Outcomes of Different Types of
Robotic Surgeries in the Different Surgical Departments: The Penta, Tetra andTrifecta Achievements in Robotic Surgeries
Takehiro Sejima,* Shuichi Morizane,* Kazunori Fujiwara,† Keigo Ashida,‡ Hiroaki Saito,‡ Yuji Taniguchi,§
Hiroshige Nakamura§ and Atsushi Takenaka**Division of Urology, Department of Surgery, School of Medicine, Tottori University Faculty of Medicine, Yonago 683-8503, Japan,†Division of Otolaryngology, Head and Neck Surgery, Department of Medicine of Sensory and Motor Organs, School of Medicine,
Tottori University Faculty of Medicine, Yonago 683-8503, Japan, ‡Division of Surgical Oncology, Department of Surgery, School of
Medicine, Tottori University Faculty of Medicine, Yonago 683-8503, Japan and §Division of General Thoracic Surgery, Department ofSurgery, School of Medicine, Tottori University Faculty of Medicine, Yonago 683-8503, Japan

ABSTRACTcancer treatment in the constitutional framework of an
academic institution. MISC, which provides the constitutional framework of an academic institution, is providing immeasurable benefits in terms of robotic surgery
quality, and it may ultimately lead to high penta-, tetra-,and trifecta rates for robotic surgeries for cancer treatment in all surgical departments.

BackgroundTo ensure safe performance in robotic
surgery, the Minimal Invasive Surgery Center (MISC) is
composed of the anesthesiology department, five surgery
departments and co-medical staff in our institution. The
objective of this study was to evaluate the outcomes ofdifferent types of robotic surgeries for cancer treatment (n= 326) from different surgery departments in the MISC.
Methods The outcomes of robot-assisted radical
prostatectomy (RARP), partial nephrectomy (RAPN),
transoral robotic surgery (TORS) for pharyngeal cancer,
and robotic surgery for lung, gastric and rectal cancer
were evaluated using the similar concept of pentafecta
in RARP.
Results The pentafecta rates of RARP and robotic
surgery for rectal cancer were 33.3 and 56.5%, respectively. The tetrafecta rates of RARP (excluding potency
evaluation from pentafecta) and TORS were 48.4 and57.1%, respectively. The trifecta rates of RAPN, robotic
surgeries for lung and gastric cancer were 75.9, 74.2 and
84.2%, respectively. The failure of tetrafecta in RARP
achievement was significantly associated with high risk
than with low risk according to National Comprehensive
Cancer Network classification.
Conclusion This is the world’s first comprehensive
evaluation of different types of robotic surgeries for

Key words evaluation; outcome; robotic surgery

Robot-assisted radical prostatectomy (RARP) using
the da Vinci surgical system started in 20001 and it has
spread rapidly while retaining the concept of minimal
invasive surgery. Although RARP was introduced in2006 in Japan, the spread of RARP has been very slow
because of the off-label application of Japanese healthinsurance over this time. However, the Japanese Ministry of Health, Labor and Welfare allowed the applicationof health insurance for RARP on April 2012; therefore,
the rapid spread of RARP is ongoing. A concern withregard to the rapid spread of new surgical innovation is
the issue of patient safety. Reduced patient safety occurs
due to insufficient preparation and inadequate surgical
techniques during the introduction of a new technology.
To eliminate such concerns, the introduction and implementation of robotic surgeries in our institution were
controlled by MISC, which performs robotic surgeries
comprehensively not only in urology but also in othersurgical departments. Recently, we reported our initial
experience of 100 patients treated by RARP with a focus
on constitutional introduction and implementation basedon MISC.2 Since the initial experience of all robotic
surgeries from different surgical departments, the casenumbers of robotic surgeries have been continuously
growing. The next aim of MISC after completion of thesafe introduction of robotic surgery is the evaluation ofrobotic surgical outcomes.
Trifecta was introduced by Bianco et al. to evaluate
the outcomes of RARP, aiming for the coexistence ofCorresponding author: Takehiro Sejima, MD, PhD
Present address: Department of Urology, Matsue City Hospital,
Matsue 690-8509, Japan
sejimat@gmail.com
Received 2016 March 7
Accepted 2016 April 15
Abbreviations: ASA, American Society of Anesthesiologists; BMI,
body mass index; CD, Clavien-Dindo; CEA, carcinoembryonicantigen; eGFR, estimated glomerular filtration rate; LPN, laparoscopic partial nephrectomy; MISC, Minimal Invasive Surgery
Center; MRI, magnetic resonance imaging; NCCN, National Comprehensive Cancer Network; PSA, prostate specific antigen; RAPN,
robot-assisted partial nephrectomy; RARP, robot-assisted radical
prostatectomy; RP, radical prostatectomy; TORS, transoral robotic
surgery; WIT, warm ischemia time135

T. Sejima et al.

cancer control and functional preservation.3 Along withincreased patient demands and greater expectations ofsurgical interventions, a new and more comprehensive
method for reporting outcomes in RARP, i.e., the pentafecta, was proposed.4 Similarly, trifecta was advocatedin robot-assisted partial nephrectomy (RAPN) for meeting high quality surgical goals, including cancer control,
functional preservation and absence of complications.5
Despite the concrete surgical goals of robotic surgeries
in the urological field, such goals seem to be obscure inrobotic surgeries in other surgical departments. There isa concern with regard to the disappearance of sustained
efforts by expert surgeons without concrete surgicalgoals. Therefore, we performed a comprehensive evaluation of the different types of robotic surgeries for cancer
treatment in MISC, which provides the constitutionalframework of our academic institution.

MATERIALS AND METHODS
The role of MISC in robotic surgery; Constitutionalframework of our institution

The urology staff started performing RARP in October2010 as the first robotic surgery in our institution. MISC
was organized six months after the first RARP, and it
consisted of all of the departments related to robotic
surgery including anesthesiology, urology, gynecology,
respiratory and digestive surgery, otorhinolaryngology,
operation room nurses, medical engineers and medical
clerks. From the viewpoint of safe implementation of robotic surgery, each surgery was performed under the supervision of MISC. For instance, certification for surgery
type and the console surgeon were authorized by MISC.
Specifically, MISC has “termination order” authority,
which is exercised when there is excessive bleeding or
an extended surgical time (Fig. 1). Robotic surgery must
be converted into another type of surgery, such as open
conversion, once the order is given. Each robotic surgery
case in all surgery departments is checked and discussed
pre- and postoperatively at the regular meetings held by
MISC twice per month.

Department: Urology

Department:

Digestive Surgery

Surgery type: Robot-assisted radical prostatectomy

Surgery type:

Robot-assisted low anterior resection(Limited lymphadenectomy)
1) Standard operation time:1) Standard operation time:

5 hours6hours2) Basal condition of termination order2) Basal condition of termination ordera) Breakdown or malfunction of robotic surgical systema) Breakdown or malfunction of robotic surgical systemb) Malfunction of robotic surgical equipmentb) Malfunction of robotic surgical equipmentc) Excess bleeding:more than 2000d) Excess operating time:

more thanmL8c) Excess bleeding:hours

more thand) Excess operating time:

500

more than

mL
10

hours

3) Other conditions of the termination order3) Other conditions of the termination ordera) When operators recognize unexpected intra-operativea) When operators recognize the difficulty of proceeding

findings of advanced cancer

with the operation based on an anatomical abnormalityb) When it is obvious that other organ injuries occur

or adhesionc) When anesthetists recognize critical problem in theb) When anesthetists recognize a critical problem in thegeneral care of the patient

general care of the patient

Fig. 1. The termination order (English version) for RARP and robotic surgery for rectal cancer is shown. The original documents are described in Japanese. RARP, robot-assisted radical prostatectomy.

136

Evaluation of robotic surgical outcome

Patients

incidence of preoperatively potent patients, comparedwith the incidence of patients in Western countries, andthe small number of patients who underwent bilateralnerve sparing procedures, the definition of potency
was modified as follows. The recovery of potency wasdefined in cases in which a preoperatively potent patient (International Index of Erectile Function erectile
function domain > 21) underwent bi- or unilateral nerve
sparing procedures and recovered to International Index
of Erectile Function erectile function domain > 17, withand without the use of PDE5 inhibitors postoperatively.
Because the patient cohort that the pentafecta rate wasable to evaluate consisted of a small number of patients,
tetrafecta rate (excluding potency evaluation) was also
evaluated in RARP. The most current use of the definition of trifecta in RAPN5 was employed in the study,i.e., warm ischemia time (WIT) less than 25 minutes,
negative surgical margins and no perioperative complications.

A total of 500 cases were treated by robotic surgeries
from October 2010 to September 2015 in MISC. Amongthese cases, 326 cases were treated by robotic surgery
for cancer therapy and followed for more than 12 months(according to the criteria of patients in the evaluation ofpentafecta4) and were enrolled in the study. The medianfollow-up duration was 24.2 months (range: 12.5–54.2).
The details of the 326 cases were RARP (n = 217),
RAPN (n = 29), robotic surgery for lung (n = 31), gastric(n = 19) and rectal (n = 23) cancers, and transoral robotic surgery (TORS) for pharyngeal cancer (n = 7) (Table1). The study was approved by the Ethics Committee of
Tottori University Faculty of Medicine (Approved No.
1602A125).
Definition of penta and tetrafecta in RARP and trifecta in RAPN

The definition of pentafecta in RARP complied withthe robust previous literature,4 with some modifications
only in the definition of potency. Because of the lower

Table 1. Robotic surgery types for cancer treatment and their number of cases
Department

Surgery typeNo. of cases

Urology

Robot-assisted radical prostatectomy (RARP)

217

Robot-assisted partial nephrectomy (RAPN)

29

Respiratory surgery

Robotic surgery for lung cancer

31

Digestive surgery

Robotic surgery for gastric cancer

19

Robotic surgery for rectal cancer

23

Transoral robotic surgery (TORS) for pharyngeal cancer

7

Otorhinolaryngology
Total

326

Table 2. Definition of penta, tetra and trifecta in each type of robotic surgery
Surgery typeDefinition of penta, tetra or trifecta achievement

RARP (Pentafecta)

1) No biochemical recurrence, 2) Negative surgical margin, 3) Continence recovery (no pad),4) Potency recovery, 5) No complication

RARP (Tetrafecta)

1) No biochemical recurrence, 2) Negative surgical margin, 3) Continence recovery (no pad),4) No complication

RAPN (Trifecta)

1) Negative surgical margin, 2) Warm ischemia time (WIT) ≤ 25 min., 3) No complication

Robotic surgery for rectal
cancer (Pentafecta)

1) No recurrence, 2) Negative surgical margin, 3) Normal voiding, 4) Normal defecation,

TORS (Tetrafecta)
Robotic surgery for lung andgastric cancer (Trifecta)

1) No recurrence, 2) Negative surgical margin, 3) Normal swallowing, 4) No complication

5) No complication
1) No recurrence, 2) Negative surgical margin, 3) No complication

RAPN, robot-assisted partial nephrectomy; RARP, robot-assisted radical prostatectomy; TORS, transoral robotic surgery; WIT, warm
ischemia time.

137

T. Sejima et al.

Definition of pentafecta in robotic surgery for rectal
cancer, tetrafecta in TORS, and trifecta in robotic
surgeries for lung and gastric cancerof the criteria. For instance, the trifecta rate in robotic
surgery for gastric cancer is the rate of cases against
total cases in which surgical outcome has met successfully “no recurrence,” “negative surgical margin” and“no complication.” The pentafecta rates of RARP (n =24) and robotic surgery for rectal cancer were 33.3 and56.5%, respectively. The tetrafecta rates of RARP (n =217) and TORS were 48.4 and 57.1%, respectively. The
trifecta rates of RAPN, robotic surgeries for lung andgastric cancer were 75.9, 74.2 and 84.2%, respectively.
The penta and tetrafecta rates of RARP, robotic surgery
for rectal cancer and TORS are shown with their radargraphs (Fig. 2). Similarly, the trifecta rates of RAPN androbotic surgery for lung and gastric cancer are shownwith their radar graphs (Fig. 3).

Because of the lack of evaluative measures for robotic
surgical outcomes in the surgical departments other thanurology, we originally defined penta, tetra and trifecta.
Considering the transition from trifecta to pentafecta
in RARP and the advocacy of trifecta in RAPN, threeissues were included, if possible, in the study, i.e., “complete cancer control,” “functional preservation” and “noperioperative complications.” The issue of “complete
cancer control” included both negative surgical margins
and no postoperative relapse except for RAPN. Because
the issue of “functional preservation” has not been established in robotic surgeries for lung and gastric cancer,
it was excluded from these two types of surgery. With
regard to the issue of “no perioperative complications,”
complications occurring during the surgical procedureor within 90 d after surgery were documented and classified according to the Clavien-Dindo (CD) classification.6 The definitions of penta, tetra or trifecta in eachtype of robotic surgery in the MISC are summarized inTable 2.

The predictive factors for achieving tri, tetra andpentafecta in each type of robotic surgery forcancer treatment

TORS was excluded from the analyses because of thesmall number of cases. The factors analyzed were patient and tumor backgrounds, which reflected patients
generally and tumors specifically. Moreover, the analyzed factors were chosen based on the concept of easy
use for clinical practice. Age, body mass index (BMI),
and the American Society of Anesthesiologists (ASA)
risk classification system score were analyzed in eachtype of robotic surgery. Other than these data, the following factors were analyzed. For RARP (penta andtetrafecta achievement), preoperative prostate specificantigen (PSA), risk stratification in the National Comprehensive Cancer Network (NCCN), T stage, Gleason
score and existence of lymph node metastasis in final
pathology were considered; for robotic surgery for rectal(pentafecta achievement), gastric (trifecta achievement)
and lung cancers (trifecta achievement), sex, preoperative carcinoembryonic antigen (CEA) and T stage infinal pathology were considered; and for RAPN (trifecta
achievement), sex, renal nephrometry score and whether
malignant or benign in final pathology were considered.
From all of the analyses, only one independent factor
was revealed that was predictive of tetrafecta achievement in RARP (Table 3), which indicated that the failureof tetrafecta achievement was significantly associatedwith high risk than with low risk according to NCCN
classification.

Statistical analysis

Univariate and multivariate logistic regression analyses
were used to analyze the factors predictive of achieving
tri, tetra and pentafecta in each type of robotic surgery,with P < 0.05 considered statistically significant.
RESULTS
The types, case numbers, complications and open
conversion rates of all robotic surgeries in the
MISC

A total of 500 cases undergoing 14 types of robotic surgery were treated from the first case of robotic surgery
until September 2015 in the MISC. Serious complications (CD grade ≥ Ⅲ) were recognized in 6 cases (1.2%).
Open conversion was performed in only one case (0.2%),
which was treated by robotic surgery for gastric cancer
not because of an emergency reason but because of difficulty in the robotic procedure due to unexpected cancer
progression.
The evaluation of robotic surgical outcomes forcancer treatment according to penta, tetra and trifecta in the MISCDISCUSSION
Almost 10 years have passed since the introduction oftrifecta in RARP, but only 11 original articles have reported trifecta rates, with a mean value of 58% (range
20–83%).7 Although the surgical goal in RARP has been

Only patients who successfully met all of the aforementioned criteria in each type of robotic surgery wereconsidered to achieve penta, tetra or trifecta. The penta,
tetra and trifecta rate (percentage) are the rates of cases in which surgical outcome has met successfully all138

Evaluation of robotic surgical outcome
RARP (pentafecta)

Robotic surgery for rectal cancer (pentafecta)
No biochemicalrecurrencen = 2480
60

NormalNegative
surgical margin defecation

40

Potency

No recurrencen = 23100

200Pentafecta
rate = 33.3%

RARP (tetrafecta)

TORS (tetrafecta)
No
recurrence

100
80

n=7

60
40
20

Continence

Tetrafecta
rate = 48.4%

No complication

Pentafecta rate = 56.5%

No biochemicalrecurrencen = 217

Negative surgicalmarginNormal voidingNo
complication

Continence

100
80
60
40
20
0

Negative
surgical margin

0

Normalswallowing

Tetrafecta
rate = 57.1%

Nocomplication

100
80
60
40
20
0

Negative
surgicalmarginNocomplication

Fig. 2. The radar graphs of penta and tetrafecta achievements in RARP and of robotic surgery for rectal cancer
and TORS are shown. In each radar graph, single components and their successful rates are also shown. RARP,
robot-assisted radical prostatectomy; TORS, transoral robotic surgery.

RAPN (trifecta)

Negative surgicalmargin100

n = 29

80

60
40
20

Trifecta rate
= 75.9%0

WIT ≤ 25 min

No complication

Robotic surgery for lung cancer (trifecta)n = 31

Robotic surgery for gastric cancer (trifecta)
No recurrence

No recurrencen = 19100
80

Nocomplication

80

60

60

Trifecta rate
= 74.2%100

Trifecta rate
= 84.2%

40
20
0

No
complication

Negative
surgicalmargin40
20
0

Negative
surgicalmarginFig. 3. The radar graphs of trifecta achievements in RAPN and robotic surgeries for lung and gastric cancer are
shown. In each radar graph, single components and their successful rates are also shown. RAPN, robot-assisted
partial nephrectomy, WIT, warm ischemia time.

139

T. Sejima et al.
Table 3. Multivariate analysis for predictive factors of achieving tetrafecta in RARP
FactorOR (95% CI)

P valueAge at surgery (ys)1.040 (0.993–1.090)

0.0949

BMI (kg/m2)

1.000 (0.899–1.111)

0.9933

ASA scoreClass Ⅰ

0.865 (0.483–1.549)

0.62461.009 (0.957–1.065)

0.7272Low

1.000 (referent)

Initial PSA (ng/mL)
NCCN risk

T stage (final pathology)

Gleason score (final pathology)

Lymph node metastasis(final pathology)

1.000 (referent)

Class ⅡIntermediate

0.627 (0.239–1.641)

0.3411High

0.346 (0.125–0.955)

0.04050, 2a1.000 (referent)

2b1.377 (0.345–5.505)

0.65062c0.824 (0.396–1.713)

0.6032≥ 3a1.186 (0.432–3.257)

0.74036

1.000 (referent)

7

1.675 (0.643–4.364)

0.2913≥8

1.332 (0.425–4.171)

0.6227

Absent1.000 (referent)

Present

0.188 (0.020–1.797)

0.1466

ASA, American Society of Anesthesiologists; BMI, body mass index; CI, confidence interval; NCCN, National Comprehensive Cancer
Network; OR, odds ratio; PSA, prostate specific antigen; RARP, robot-assisted radical prostatectomy; ys, years.

changed from trifecta to pentafecta, the number of studies indicating pentafecta rates has been limited. Three
major studies, in which more than one hundred patientswere treated by RARP, demonstrated pentafecta rates of
70.8, 60.4 and 45.6%, respectively. 4, 8, 9 There have been
criticisms that trifecta and pentafecta systems are notappropriate reporting tools for the majority of patients
undergoing radical prostatectomy (RP) because they are
only applicable in preoperatively continent and potent
patients who receive bilateral nerve-sparing procedures.
Recently, the survival, continence, and potency, so
called SCP classification, has been advocated to classify
appropriately all patients who undergo RP according tothe oncologic and functional outcomes of relevance tothem on an individual basis.7 The diverse sexual activity
and desire of patients treated by RP worldwide definitely affects the usefulness of the pentafecta system.
In Asian patient cohorts, only one study demonstrated
a pentafecta rate of 72.9% in 170 patients treated bylaparoscopic RP.10 It is presumed that patients’ sexual
activity and desire in Japan are lower than those of patients from Western countries. Moreover, the relatively
high incidence of patients in Japan who underwent plain
localization of cancer foci in the prostate by frequent
use of magnetic resonance imaging (MRI) indicatedunilateral rather than bilateral nerve-sparing procedures.
Therefore, we investigated for the first time worldwide
the tetrafecta rate, excluding the potency term from pentafecta, in patients treated by RARP. Because there havebeen no studies indicating tetrafecta rates, our resultof 48.4% should be considered a pilot value. Our study
demonstrated that the failure of tetrafecta achievement
was significantly associated with high risk than withlow risk according to NCCN classification. Because we
performed extended lymphadenectomy and wide dissection of the prostate in high risk patients, it seemed to be
the necessary consequence that high risk according to
NCCN classification was revealed as factor predictive of
the failure of tetrafecta.
There has been a debate over the definition offunctional preservation in trifecta for RAPN. Hung etal. demonstrated the outcomes of 534 patients treated by laparoscopic partial nephrectomy (LPN) and
RAPN based on the trifecta concept, with failure of
renal functional preservation defined as a greater than
10% reduction in the actual estimated glomerular filtration rate (eGFR), compared with that of the volume
predicted postoperative eGFR rate.11 In contrast, Buffi
et al. proposed an evaluation measure called “MIC”(margin, ischemia and complications) in nephron spar140

Evaluation of robotic surgical outcome

ing surgery.12 Hung et al. argued that ischemia was notnecessarily the most important surgical factor affecting
postoperative renal function. However, the majority ofstudies have defined WIT < 25 min. as an indicator offunctional preservation, based on a study indicating a
cut-off time for warm ischemia in solitary kidney cases
treated by partial nephrectomy.13 Trifecta rates of RAPN
have been demonstrated, in the setting of retrospective
comparison between LPN and RAPN, as 58.7 and 70%
derived from 251 and 1185 cases treated by RAPN, respectively.5, 14 If having complications with ≤ CD grade
Ⅱ was defined as a successful criterion, the trifecta rateincreased to 81.8 % in 44 cases treated by RAPN.15 Although the number of cases in our cohort was lower thanthose in the aforementioned studies, our trifecta rateof 75.9% in RAPN seemed to be excellent. This result
might have three causes. The first is the expert skill of
the surgeon (Co-author; A.T.), who had sufficient experience in LRP and RARP. Unlike RARP, all cases of
RAPN were performed by him. The second cause was
the MISC management, especially the regular conferences at which all robotic cases were assessed pre- andpostoperatively. The third was the intraoperative navigation system used, with SYNAPSE VINCENT (Fujifilm,
Tokyo, Japan) film technology, which could draw renal
vascular images precisely.
First, there was no other way to recognize our results of penta, tetra and trifecta in robotic surgeries otherthan using the urological field for pilot values because
no studies have been conducted previously. However, it
is universal to use the items of “complete cancer control”
and “no perioperative complication” in the evaluation of
the surgical outcome for various kinds of cancer treatment. To unify the matter of complete cancer control inthe study, negative surgical margins and no postoperative relapse were employed in all of the robotic surgery
types except for RAPN. However, there were no studies
investigating surgical margin status in robotic surgeries for lung or gastric cancer. Complete cancer control
should be evaluated in the future employing other factors
in these two types of robotic surgery because there aresome potent prognostic indicators, such as lymph nodepathology, especially in gastric cancer. In the comparison of cancer control between robotic and laparoscopic
surgeries for rectal cancer, circumferential and distal
resected margin positive rates were demonstrated as being equivalent between the two approaches.16–19 In contrast, the positive surgical margin rate of 4.3% in TORS,
which was indicated from a prospective, multicenter
study, was suggested not to be inferior to other types oftransoral minimally invasive surgeries.20 In our study,
the positive surgical margin rates with robotic surgery

for rectal cancer and TORS were 0% and 28.6%, respectively. However, the evaluation of TORS was difficult
because of the small number of cases in our study (n = 7).
With regard to evaluation of visceral functionalpreservation in robotic surgeries with penta, tetra andtrifecta other than in urological field, we chose someappropriate and established items. “Normal defecation”
and “normal voiding” have been established in the evaluation of robotic surgery for rectal cancer as well as“normal swallowing” in the evaluation of TORS. Voiding and sexual function were demonstrated to be better
after robotic surgery than after laparoscopic surgery forrectal cancer using uroflowmetry and questionnaires.21, 22
The functional preservation of voiding and defecation,rather than sexual function, based on the collectable datain our study, was generally satisfactory (18 of 23 cases;
78.3%). Percutaneous endoscopic gastrostomy dependency after TORS which was defined as the surrogate
factor for swallowing evaluation reported in 5% of cases,
and the rate was equivalent to those in other treatment
modalities for oropharyngeal malignancy.20 Finally, thecomplication rates in all types of robotic surgery, except
RARP and RAPN, were demonstrated to be better thanor equivalent to those in open or other minimally invasive surgeries.23–26 Although complications occurred in
12 of 23 cases (52.2%) in robotic surgery for rectal cancer, most of them (11 of 12 cases) were minor (CD grade≤ Ⅱ). In other types of robotic surgery, the complication
rates were generally low in our study.
Our study has certain limitations. The first is that
there were no data with regard to penta, tetra or trifecta
rates in robotic surgeries other than from the urological field. Even the concept of these surgical goals was
not present. Therefore, our data were only pilot values.
However, the first trial of the evaluation of robotic surgical outcomes, based on the concept of penta, tetra
and trifecta, in surgical departments other than urology
should be initiated in urology because urologists are thepioneers of robotic surgery. Other limitations include
the retrospective nature of the study, as well as its single-center trial design and the small sample size. External validation of the penta, tetra and trifecta rates in all
types of robotic surgery for cancer treatment will facilitate the comprehensive evaluation of robotic surgicaloutcomes not only in urology but also in other surgicalfields.
In conclusion, the world’s first comprehensive evaluation of different types of robotic surgeries for cancer
treatment in the constitutional framework of an academic institution could result in the safer implementation ofrobotic surgeries with higher quality. MISC is a useful
construction that can evaluate robotic surgical outcomes141

T. Sejima et al.

based on the same measures that extend across theboundaries among different surgical departments. Although penta, tetra and trifecta rates in surgical departments other than urology are only pilot values, it is valid
to initiate a comprehensive evaluation of robotic surgicaloutcomes using data from urologists, who are the pioneers of robotic surgery.

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13 Thompson RH, Lane BR, Lohse CM, Leibovich BC, Fergany A,
Frank I, et al. Every minute counts when the renal hilum isclamped during partial nephrectomy. Eur Urol. 2010;58:340-5.
PMID: 20825756.
14 Zargar H, Allaf ME, Bhayani S, Stifelman M, Rogers C,
Ball MW, et al. Trifecta and optimal perioperative outcomesof robotic and laparoscopic partial nephrectomy in surgicaltreatment of small renal masses: a multi-institutional study.
BJU Int. 2015;116:407-14. PMID: 25220543.
15 Carneiro A, Sivaraman A, Sanchez-Salas R, Di Trapani E,
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The authors declare no conflict of interest.

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