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World J Gastrointest Endosc. Feb 16, 2015; 7(2): 121-127
Published online Feb 16, 2015. doi: 10.4253/wjge.v7.i2.121
Circumstance of endoscopic and laparoscopic treatments for gastric cancer in Japan: A review of epidemiological studies using a national administrative database
Atsuhiko Murata, Shinya Matsuda, Department of Preventive Medicine and Community Health, School of Medicine, University of Occupational and Environmental Health, Yahatanishi-ku, Kitakyushu 807-8555, Japan
Author contributions: Murata A and Matsuda S contributed to this paper.
Conflict-of-interest: All authors have no conflicts of interest to declare.
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Correspondence to: Atsuhiko Murata, MD, PhD, Department of Preventive Medicine and Community Health, School of Medicine, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan. amurata@med.uoeh-u.ac.jp
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Received: June 16, 2014
Peer-review started: June 16, 2014
First decision: July 17, 2014
Revised: November 10, 2014
Accepted: November 27, 2014
Article in press: December 1, 2014
Published online: February 16, 2015
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Abstract

Currently, endoscopic submucosal dissection (ESD) and laparoscopic gastrectomy (LG) have become widely accepted and increasingly play important roles in the treatment of gastric cancer. Data from an administrative database associated with the diagnosis procedure combination (DPC) system have revealed some circumstances of ESD and LG in Japan. Some studies demonstrated that medical costs or length of stay of patients receiving ESD for gastric cancer had become significantly reduced while length of hospitalization and costs were significantly increased in older patients. With respect to LG, some recent reports have shown that this has been a cost-beneficial treatment for patients compared with open gastrectomy while simultaneous LG and cholecystectomy is a safe procedure for patients with both gastric cancer and gallbladder stones. These epidemiological studies using the administrative database in the DPC system closely reflect clinical circumstances of endoscopic and surgical treatment for gastric cancer in Japan. However, DPC database does not contain detailed clinical data such as histological types and lesion size of gastric cancer. The link between the DPC database and another detailed clinical database may be vital for future research into endoscopic and laparoscopic treatments for gastric cancer.

Key Words: Gastric cancer; Endoscopic submucosal dissection; Laparoscopic gastrectomy; Diagnosis Pro-cedure Combination; Administrative database; Epide-miological studies

Core tip: Currently, endoscopic submucosal dissection (ESD) and laparoscopic gastrectomy (LG) have become accepted for treatment of gastric cancer and increasingly played important roles on the treatments of gastric cancer in Japan. Using the database on national administrative database associated with the diagnosis procedure combination (DPC) system, the various studies with regards to ESD and LG for gastric cancer have been revealed. We herein describe the circumstance of ESD and LG for gastric cancer in Japan based on reports using Japanese administrative database associated in the DPC system in this review.
INTRODUCTION

Gastric cancer is one of the most frequent cancers and causes of cancer-related deaths[1,2]. Although a trend of declining incidence has been observed, gastric cancer still causes a great health care burden[3]. According to the report by the Ministry of Health, Labour and Welfare of Japan (MHLW), roughly 50000 Japanese people die due to gastric cancer annually, representing 15% of cancer-related deaths[2]. Therefore, health care policies for gastric cancer are increasingly focused on detection and treatment in the early stage because the 5-year cancer survival in the early stage of gastric cancer has been reported to be greater than 90%[4,5]. Almost half of gastric cancers have been discovered at an early stage because of early detection measures[6].

Regarding the endoscopic treatments for early gastric cancer, endoscopic mucosal resection (EMR) was standard practice[6]. However, significant progress in endoscopic treatment has contributed to more effective resection of early gastric cancer. Endoscopic submucosal dissection (ESD) has achieved a high rate of histologically curative en bloc resection for early gastric cancer regardless of size, permitting the resection of previously non-resectable tumors. The ESD technique has spread rapidly owing to its excellent eradication rate compared with EMR[6-8]. ESD is recognized as an established endoscopic therapy for the treatment of early gastric cancer[8-10].

Although almost early gastric cancers can be treated by ESD, the number of surgical operation for gastric cancer still remains high. Also in the field of surgical treatments, recent advances have allowed more effective and safe procedure for gastric cancer. Laparoscopic gastrectomy (LG) is significantly less invasive than open gastrectomy (OG), with lower mortality and morbidity rates[11-13]. Furthermore, LG is now performed not only as distal gastrectomy but also as proximal and total gastrectomy[11-13]. Currently, LG has been accepted for the treatment of gastric cancer, with the number of patients requiring this surgical procedure increasing in Japan, as well as other developed countries[13-15].

Currently, endoscopic and laparoscopic treatments such as ESD and LG are increasingly playing important roles for the treatment of gastric cancer. In this review, we report the circumstances of ESD and LG for gastric cancer in Japan, based on reports using Japanese administrative database associated with the diagnosis procedure combination (DPC) system.

ADMINISTRATIVE DATABASE ASSOCIATED WITH THE DPC SYSTEM
History of the DPC system

The health care system of Japan has severe problems owing to the expense of new medical technology and extended hospitalizations of patients[16]. To solve these problems, the MHLW started to investigate whether the case-mix classification system can be adopted to standardize medical profiling and payment[16-20]. In 2003, Japanese case-mix projects based on the DPC system were introduced to 80 university and 2 national hospitals.

DPC participating hospitals have adopted a unique reimbursement system, whereby the paid medical treatment fees become proportionally higher as the length of stay (LOS) becomes shorter. Therefore, a shorter hospitalization leads to an increase in income for the hospitals. Furthermore, payment per hospitalization is strictly determined by the DPC payment system. Currently, the number of DPC-participating hospitals has been increasing. Enormous amounts of data on hospitalization of patients have been collected annually, covering roughly 55% of the total hospitalizations, according to the report from the MHLW in 2014[21].

Component of data in the DPC system

This system collects important data during hospitalization in addition to the characteristics of the unique reimbursement system. Each patient’s background information or discharge summary, which includes principal diagnosis, complications, comorbidities, and outcomes are recorded in the administrative database associated with the DPC system. These patient data are coded using the International Classification of Diseases and Injuries 10th Revision (ICD-10th) code. Also, this database includes the hospital information, number and date of clinical procedures, such as operations or drug therapies that are indexed in the original code determined by the MHLW[16-20]. Detailed contents of data in the database of the DPC system are shown in Table 1[22].

Table 1 Contents of data in the national administrative database[22].
Hospital information
Location of hospital
Number of beds
Patient background information
Age
Sex
Zip code
Diagnoses
Main diagnoses (coded with International Classification of Diseases and Injuries 10th Revision
(ICD-10th) code)
Main diagnoses (coded with the ICD-10th codes)
Complications after admission (coded with the ICD-10th codes)
Procedures for patients
Surgery, anesthesia and other procedures (coded with the Japanese original codes)
Drugs and devices (coded with the Japanese original codes)
Dates of each procedure
Dates of use for each drug and device
Admission and discharge data
Urgent or elective admission
Ambulance service use
Dates of admission and discharge; length of stay
Discharge status (discharge to home, rehabilitation hospital or other facility, or death)
Claim data
Total charge
Itemized charges for hospitalization, medication, examination, surgery and others
Other clinical data
Height/body weight
Smoking index
Pregnancy
Japan Coma Scale at admission
TNM classification of malignant tumors
Activity of Daily Living scale
Modified Rankin scale
Hugh-Jones classification of respiratory status
New York Heart Association classification of heart failure symptoms
Canadian Cardiovascular Society classification of angina pectoris
Killip classification of acute myocardial infarction
Severity classification of community-acquired pneumonia
Child-Pugh classification of liver cirrhosis
Severity classification of acute pancreatitis
Burn index
Global Assessment of Functioning scale
Collection and use of DPC data

Comprehensive surveys of DPC-participating hos-pitals are conducted by the DPC research group that has worked on the DPC data utilization project for research purposes, independently of the MHLW. DPC-participating hospitals sent the anonymized and provided detailed data to the DPC research group, which then sent to the server in the DPC research group. Using the sent data from DPC-participating hospitals, many studies have been reported in the various fields of medical research[16-20,23-26].

EPIDEMIOLOGICAL STUDIES ON ESD FOR GASTRIC CANCER USING DPC DATABASE
ESD for gastric cancer (Table 2)
Table 2 Reports of endoscopic and laparoscopic treatments for gastric cancer using national administrative database.
No. of patientsNo. of hospitalsStudy periodInvestigated outcomes
Endoscopic submucosal dissection
Murata et al[27]329439072009-2011Complications, length of stay, and medical costs
Murata et al[30]273858672009-2011Complications and length of stay
Murata et al[36]273858672009-2011Complications, length of stay, and medical costs
Laparoscopic gastrectomy
Yasunaga et al[40]93888052010Complications, length of stay, medical costs, in-hospital mortality and 30-d readmission rates
Kuwabara et al[41]177612582006-2008Length of hospital stay, medical costs and operative time
Murata et al[42]140067442009-2011Complications, length of stay, medical costs and in-hospital mortality
Kuwabara et al[46]30544202007Complications and operative time
Kuwabara et al[47]39142582006-2008Complications, length of stay, medical costs, in-hospital mortality and blood transfusions
Ryu et al[48]20952007-2008Length of hospital stay (pre and post operative) and duration of antibiotic administration and post operative fasting

Time trend of outcomes of ESD in Japan: According to the report about the time trend of outcomes of ESD in Japan, the rate of ESD-related complications was stable (3.2% in 2009 vs 3.5% in 2010 vs 3.3% in 2011, P = 0.496) between 2009 and 2011[27]. In the early 2000s, some clinical studies in single centers reported that the complication rate of ESD was from 5% to 8%[28,29]. However, the complication rate of ESD based on an administrative database was approximately 3% between 2009 and 2011, which indicated that complications of ESD remained low. Therefore, the decrease in complication rates may suggest that the number of experienced endoscopists has been increasing between the early and late 2000s, and their technical skill level in ESD has been favorably stable from 2009 to 2011. In addition, the LOS and medical costs of patients had become significantly reduced in Japan (10.5 d in 2009 vs 9.8 d in 2010 vs 9.5 d in 2011 and 6768.4 US dollars in 2009 vs 6507.7 US dollars in 2010 vs 6427.6 US dollars in 2011; P < 0.001, respectively)[27]. The efficiency of ESD for gastric cancer as well as stable technical skills has been progressing in Japan.

Outcomes of ESD in high-volume hospitals: With respect to the report about hospital characteristics such as hospital volume, ESD-related complications were significantly lower in higher-volume hospitals (> 100 cases between 2009 and 2011) than lower- (< 50 cases) or medium-volume hospitals (50-100 cases) in upper gastric cancer (6.5% in lower-volume hospitals vs 5.2% in medium-volume hospitals vs 3.4% in higher-volume hospitals; P = 0.017)[30]. Multivariate logistic regression analysis also revealed that high-volume hospitals were significantly associated with a decrease of relative risk of ESD-related complications in upper gastric cancer [odds ratio (OR) for higher-volume hospitals 0.51; 95% confidence interval (CI), 0.32-0.81, P = 0.005]. Meanwhile, no significant differences for ESD-related complications were seen for middle and lower gastric cancers among the different hospital volume categories (P > 0.05)[30]. Some previous studies also pointed out that a higher skill level with ESD is required for upper gastric cancers than for middle or lower gastric cancers[31-33]. Higher volume hospitals were more likely to have experienced endoscopists can provide sufficient treatment, which significantly contributed to fewer complications or shorter LOS[34,35]. Thus, it is reasonable that the decreases in ESD-related complications and in LOS of patients with upper gastric cancer were observed at higher-volume hospitals.

Comparison between non-elderly and elderly patients treated by ESD: A comparison between elderly (80 years or more) and non-elderly patients (less than 80 years) regarding outcome of ESD was also reported[36]. A recent study revealed that there was no statistically difference with regard to ESD-related complications (3.9% vs 4.3%, P = 0.152)[36]. The findings about complications of ESD has been consistent with those of some previous studies in Japan[37,38]. Kakushima et al[37] showed that the complication rate of ESD in elderly patients was not significantly different from that in non-elderly patients, while Tokioka et al[38] also reported that the occurrences of perforations during ESD were similar in non-elderly and elderly patients. However, length of hospitalization and direct costs during hospitalization were significantly increased in elderly patients requiring ESD for gastric cancer, compared with non-elderly patients (12.2 d vs 9.3 d and 7346.3 US dollars vs 6295.6 US dollars; P < 0.001, respectively). The growing life expectancy and an aging population will unavoidably lead to an increasing number of elderly patients in Japan[39]. Therefore, providing appropriate care in endoscopic treatments for elderly patients is becoming significantly important in Japan. More efficient medical implementation for elderly patients with gastric cancer treated with ESD will be required in the future.

LG for gastric cancer

Comparison between LG and OG for gastric cancer: Using the data in 2010, Yasunaga et al[40] reported that patients treated by LG had shorter LOS compared with those with OG (13 d vs 15 d, P < 0.001) while no significant difference was observed in mortality and occurrence of postoperative complications (LG vs OG, 0.36% vs 0.28%, P = 0.80 and 12.9% vs 12.6%, P = 0.73, respectively). Kuwabara et al[41] also reported that LG offered a significant economic advantage over OG (14405 US dollars vs 17260 US dollars, P < 0.001). These results show that LG has been a beneficial treatment for patients who require surgical resection for gastric cancer.

Influence of additional laparoscopic cho-lecystectomy on outcomes of LG for gastric cancer: A recent report revealed that adding laparoscopic cholecystectomy did not influence to outcomes of patients undergoing LG for gastric cancer (OR for laparoscopy-related complications 1.02, 95%CI: 0.84-1.24, P = 0.788 and OR for in-hospital mortality 1.16, 95%CI: 0.49-2.76, P = 0.727)[42]. These results have been consistent with previous studies in other developed countries[43,44]. The greater surgeon’s experience and continuing technical progress for laparoscopic resection has resulted in expanded indications in Japan[42]. Besides, there has been an increase in the types of surgical operations together with laparoscopic procedure, and the number of surgeons interested in simultaneous laparoscopic procedures has increased[45]. Thus these results indicate that the combined LG and cholecystectomy is safe procedure for patients with both gastric cancer and gallbladder stones.

Impact of hospitals and regional differences for outcomes of LG for gastric cancer in Japan: With regard to hospital characteristics in LG for gastric cancer, several studies reported that higher-volume hospitals had shorter operation times and postoperative LOS of patients compared with low case-volume hospitals[46,47]. In an analysis of regional differences in LG for gastric cancer, Ryu et al[48] reported that there were significant differences with respect to rate of laparoscopic resection or duration of antibiotic administration between cancer centers of different regions. In addition, their report revealed that significant variation in pre- or postoperative LOS was observed between hospitals. Such reports could contribute to the quality of medical care for patients, which could have significant implications for decision making of health care policy in Japan.

ADVANTAGE OF EPIDEMIOLOGICAL STUDIES USING DPC DATABASE

Unlike the single center study, these studies have been conducted based on a nationally representative sample of patients in a community setting. One of the advantages of the clinical epidemiological studies using DPC data is that they facilitated evaluation of a large sample of patients in unbiased manner[16-20]. Usually, ESD and LG are performed in hospitals that have more experienced endoscopists or surgeons as well as more resources or availa-ble facilities. The DPC participating hospitals play important roles in providing advanced care or me-dical studies, as well as educating students and medical residents[16-20]. Furthermore, medical data with regards to procedures or medications have been extensively indexed with original codes[16-20]. These data are recorded on a daily basis for each patient[16-20]. Therefore, this administrative database also enables to evaluate the clinical outcomes with detailed medical treatments, in particular for medical economic outcomes. The epidemiological studies using the DPC database directly reflect the present circumstances of endoscopic or surgical treatment for gastric cancer in Japan.

LIMITATIONS OF EPIDEMIOLOGICAL STUDIES USING DPC DATABASE

Some potential limitations of clinical epidemiological studies using DPC data also should be acknowledged. This database does not contain patient data such as lesion size, histological type and staging of gastric cancer. It is reasonable that the lack of these data may influence the results of the studies using the DPC database. In addition, the types of devices for ESD or the kinds of stapling devices used for laparoscopic resection have not been included in the DPC database. Therefore, DPC data may be currently unsuitable to the detailed clinical investigation of ESD and LG for gastric cancer.

FUTURE IMPLEMENTATION

To resolve the lack of detailed clinical data, a link between our database and the other database may be vital for future research about ESD and LG for gastric cancer in Japan. The Japanese Gastric Cancer Association (JGCA) began a project to register patients who were treated by ESD since 2011[49]. In addition, some studies has been reported using the data of the National Clinical Database (NCD)[50,51]. The results from the database of this project will be useful information for the quality of ESD and LG for gastric cancer in the near future. However, we consider that more valuable information can be produced by a link between our administrative database and the database in this project. For example, the Surveillance, Epidemiology and End Results program of cancer registries, which is a cancer registry database in the United States, has been linked to the Medicare Claim Database, a payment system for medical services. As a result, many clinical studies have reported using these linked databases[52]. Therefore, we believe that a link between our database and the database of the JGCA or NCD may be vital for future research for ESD and LG for gastric cancer in Japan. If this is carried out, more valuable information showing the favorable quality of ESD for gastric cancer can be expected in patients who undergo ESD and LG for gastric cancer (Figure 1).

Figure 1
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Figure 1 Framework for future clinical epidemiological studies. DPC: Diagnosis procedure combination.
CONCLUSION

From recent studies using the national administrat-ive database, the various circumstances of endosco-pic and laparoscopic treatments for gastric cancer are revealed. These findings are useful for future studies of the treatments of gastric cancer, which could in turn have important implications for care of patients with gastric cancer in Japan. However, this administrative database is still lacking detailed clinical data of gastric cancer. The link between the administrative database and the other detailed clinical database may be vital for future research into endoscopic and laparoscopic treatments for gastric cancer in Japan.

Footnotes

P- Reviewer: Ding SZ, Sonoda H S- Editor: Ji FF L- Editor: A E- Editor: Zhang DN

References
1.  Catalano V, Labianca R, Beretta GD, Gatta G, de Braud F, Van Cutsem E. Gastric cancer. Crit Rev Oncol Hematol. 2009;71:127-164.  [PubMed]  [DOI]  [Cited in This Article: ]
2.  Lin Y, Ueda J, Kikuchi S, Totsuka Y, Wei WQ, Qiao YL, Inoue M. Comparative epidemiology of gastric cancer between Japan and China. World J Gastroenterol. 2011;17:4421-4428.  [PubMed]  [DOI]  [Cited in This Article: ]
3.  Inoue M, Tsugane S. Epidemiology of gastric cancer in Japan. Postgrad Med J. 2005;81:419-424.  [PubMed]  [DOI]  [Cited in This Article: ]
4.  Kitano S, Shiraishi N, Uyama I, Sugihara K, Tanigawa N. A multicenter study on oncologic outcome of laparoscopic gastrectomy for early cancer in Japan. Ann Surg. 2007;245:68-72.  [PubMed]  [DOI]  [Cited in This Article: ]
5.  Uedo N, Takeuchi Y, Ishihara R. Endoscopic management of early gastric cancer: endoscopic mucosal resection or endoscopic submucosal dissection: data from a Japanese high-volume center and literature review. Ann Gastroenterol. 2012;25:281-290.  [PubMed]  [DOI]  [Cited in This Article: ]
6.  Oka S, Tanaka S, Kaneko I, Mouri R, Hirata M, Kawamura T, Yoshihara M, Chayama K. Advantage of endoscopic submucosal dissection compared with EMR for early gastric cancer. Gastrointest Endosc. 2006;64:877-883.  [PubMed]  [DOI]  [Cited in This Article: ]
7.  Akahoshi K, Akahane H. A new breakthrough: ESD using a newly developed grasping type scissor forceps for early gastrointestinal tract neoplasms. World J Gastrointest Endosc. 2010;2:90-96.  [PubMed]  [DOI]  [Cited in This Article: ]
8.  Akahoshi K, Akahane H, Motomura Y, Kubokawa M, Itaba S, Komori K, Nakama N, Oya M, Nakamura K. A new approach: endoscopic submucosal dissection using the Clutch Cutter® for early stage digestive tract tumors. Digestion. 2012;85:80-84.  [PubMed]  [DOI]  [Cited in This Article: ]
9.  Białek A, Wiechowska-Kozłowska A, Pertkiewicz J, Karpińska K, Marlicz W, Milkiewicz P, Starzyńska T. Endoscopic submucosal dissection for the treatment of neoplastic lesions in the gastrointestinal tract. World J Gastroenterol. 2013;19:1953-1961.  [PubMed]  [DOI]  [Cited in This Article: ]
10.  Herreros de Tejada A. ESD training: A challenging path to ex-cellence. World J Gastrointest Endosc. 2014;6:112-120.  [PubMed]  [DOI]  [Cited in This Article: ]
11.  Choi YY, Bae JM, An JY, Hyung WJ, Noh SH. Laparoscopic gastrectomy for advanced gastric cancer: are the long-term results comparable with conventional open gastrectomy? A systematic review and meta-analysis. J Surg Oncol. 2013;108:550-556.  [PubMed]  [DOI]  [Cited in This Article: ]
12.  Chen K, Xu XW, Mou YP, Pan Y, Zhou YC, Zhang RC, Wu D. Systematic review and meta-analysis of laparoscopic and open gastrectomy for advanced gastric cancer. World J Surg Oncol. 2013;11:182.  [PubMed]  [DOI]  [Cited in This Article: ]
13.  Bencini L, Bernini M, Farsi M. Laparoscopic approach to gastrointestinal malignancies: toward the future with caution. World J Gastroenterol. 2014;20:1777-1789.  [PubMed]  [DOI]  [Cited in This Article: ]
14.  Kodera Y, Fujiwara M, Ohashi N, Nakayama G, Koike M, Morita S, Nakao A. Laparoscopic surgery for gastric cancer: a collective review with meta-analysis of randomized trials. J Am Coll Surg. 2010;211:677-686.  [PubMed]  [DOI]  [Cited in This Article: ]
15.  Mamidanna R, Almoudaris AM, Bottle A, Aylin P, Faiz O, Hanna GB. National outcomes and uptake of laparoscopic gastrectomy for cancer in England. Surg Endosc. 2013;27:3348-3358.  [PubMed]  [DOI]  [Cited in This Article: ]
16.  Murata A, Matsuda S, Mayumi T, Yokoe M, Kuwabara K, Ichimiya Y, Fujino Y, Kubo T, Fujimori K, Horiguchi H. A descriptive study evaluating the circumstances of medical treatment for acute pancreatitis before publication of the new JPN guidelines based on the Japanese administrative database associated with the Diagnosis Procedure Combination system. J Hepatobiliary Pancreat Sci. 2011;18:678-683.  [PubMed]  [DOI]  [Cited in This Article: ]
17.  Murata A, Matsuda S. Association between ambulance distance to hospitals and mortality from acute diseases in Japan: national database analysis. J Public Health Manag Pract. 2013;19:E23-E28.  [PubMed]  [DOI]  [Cited in This Article: ]
18.  Murata A, Matsuda S, Kuwabara K, Ichimiya Y, Matsuda Y, Kubo T, Fujino Y, Fujimori K, Horiguchi H. Association between hospital volume and outcomes of elderly and non-elderly patients with acute biliary diseases: a national administrative database analysis. Geriatr Gerontol Int. 2013;13:731-740.  [PubMed]  [DOI]  [Cited in This Article: ]
19.  Murata A, Okamoto K, Matsuda S, Kuwabara K, Ichimiya Y, Matsuda Y, Kubo T, Fujino Y. Multivariate analysis of factors influencing length of hospitalization and medical costs of cholecystectomy for acute cholecystitis in Japan: a national database analysis. Keio J Med. 2013;62:83-94.  [PubMed]  [DOI]  [Cited in This Article: ]
20.  Murata A, Okamoto K, Mayumi T, Maramatsu K, Matsuda S. Age-related differences in outcomes and etiologies of acute abdominal pain based on a national administrative database. Tohoku J Exp Med. 2014;233:9-15.  [PubMed]  [DOI]  [Cited in This Article: ]
21.  Ministry of Health, Welfare and Labor of Japan. [Accessed May 1, 2014].  Available from: http: //www.mhlw.go.jp/file/05-Shingikai-12404000-Hokenkyoku-Iryouka/0000041708.pdf.  [PubMed]  [DOI]  [Cited in This Article: ]
22.  The Diagnosis Procedure Combination (DPC) Database. [Accessed May 1, 2014].  Available from: http://plaza.umin.ac.jp/~hmp/cgi-bin/wiki/wiki.cgi?page=DPCDatabase.  [PubMed]  [DOI]  [Cited in This Article: ]
23.  Yamashita K, Ikai H, Nishimura M, Fushimi K, Imanaka Y. Effect of certified training facilities for intensive care specialists on mortality in Japan. Crit Care Resusc. 2013;15:28-32.  [PubMed]  [DOI]  [Cited in This Article: ]
24.  Fukuda T, Yasunaga H, Horiguchi H, Ohe K, Fushimi K, Matsubara T, Yahagi N. Health care costs related to out-of-hospital cardiopulmonary arrest in Japan. Resuscitation. 2013;84:964-969.  [PubMed]  [DOI]  [Cited in This Article: ]
25.  Nakamura M, Yasunaga H, Haraguchi T, Ando S, Sugihara T, Horiguchi H, Ohe K, Matsuda S, Fushimi K. Length of mechanical restraint following haloperidol injections versus oral atypical antipsychotics for the initial treatment of acute schizophrenia: a propensity-matched analysis from the Japanese diagnosis procedure combination database. Psychiatry Res. 2013;209:412-416.  [PubMed]  [DOI]  [Cited in This Article: ]
26.  Hamada T, Yasunaga H, Nakai Y, Isayama H, Horiguchi H, Matsuda S, Fushimi K, Koike K. Severe bleeding and perforation are rare complications of endoscopic ultrasound-guided fine needle aspiration for pancreatic masses: an analysis of 3,090 patients from 212 hospitals. Gut Liver. 2014;8:215-218.  [PubMed]  [DOI]  [Cited in This Article: ]
27.  Murata A, Okamoto K, Muramatsu K, Matsuda S. Time trend of medical economic outcomes of endoscopic submucosal dissection for gastric cancer in Japan: a national database analysis. Gastric Cancer. 2014;17:294-301.  [PubMed]  [DOI]  [Cited in This Article: ]
28.  Saito Y, Uraoka T, Matsuda T, Emura F, Ikehara H, Mashimo Y, Kikuchi T, Fu KI, Sano Y, Saito D. Endoscopic treatment of large superficial colorectal tumors: a case series of 200 endoscopic submucosal dissections (with video). Gastrointest Endosc. 2007;66:966-973.  [PubMed]  [DOI]  [Cited in This Article: ]
29.  Ono H, Hasuike N, Inui T, Takizawa K, Ikehara H, Yamaguchi Y, Otake Y, Matsubayashi H. Usefulness of a novel electrosurgical knife, the insulation-tipped diathermic knife-2, for endoscopic submucosal dissection of early gastric cancer. Gastric Cancer. 2008;11:47-52.  [PubMed]  [DOI]  [Cited in This Article: ]
30.  Murata A, Okamoto K, Muramatsu K, Matsuda S. Endoscopic submucosal dissection for gastric cancer: the influence of hospital volume on complications and length of stay. Surg Endosc. 2014;28:1298-1306.  [PubMed]  [DOI]  [Cited in This Article: ]
31.  Yoshinaga S, Gotoda T, Kusano C, Oda I, Nakamura K, Takayanagi R. Clinical impact of endoscopic submucosal dissection for superficial adenocarcinoma located at the esophagogastric junction. Gastrointest Endosc. 2008;67:202-209.  [PubMed]  [DOI]  [Cited in This Article: ]
32.  Teoh AY, Chiu PW, Wong SK, Sung JJ, Lau JY, Ng EK. Difficulties and outcomes in starting endoscopic submucosal dissection. Surg Endosc. 2010;24:1049-1054.  [PubMed]  [DOI]  [Cited in This Article: ]
33.  Sugimoto T, Okamoto M, Mitsuno Y, Kondo S, Ogura K, Ohmae T, Mizuno H, Yoshida S, Isomura Y, Yamaji Y. Endoscopic submucosal dissection is an effective and safe therapy for early gastric neoplasms: a multicenter feasible study. J Clin Gastroenterol. 2012;46:124-129.  [PubMed]  [DOI]  [Cited in This Article: ]
34.  Provenzale D, Ofman J, Gralnek I, Rabeneck L, Koff R, McCrory D. Gastroenterologist specialist care and care provided by generalists--an evaluation of effectiveness and efficiency. Am J Gastroenterol. 2003;98:21-28.  [PubMed]  [DOI]  [Cited in This Article: ]
35.  Murata A, Matsuda S, Kuwabara K, Fujino Y, Kubo T, Fujimori K, Horiguchi H. Impact of hospital volume on clinical outcomes of endoscopic biliary drainage for acute cholangitis based on the Japanese administrative database associated with the diagnosis procedure combination system. J Gastroenterol. 2010;45:1090-1096.  [PubMed]  [DOI]  [Cited in This Article: ]
36.  Murata A, Muramatsu K, Ichimiya Y, Kubo T, Fujino Y, Matsuda S. Endoscopic submucosal dissection for gastric cancer in elderly Japanese patients: an observational study of financial costs of treatment based on a national administrative database. J Dig Dis. 2014;15:62-70.  [PubMed]  [DOI]  [Cited in This Article: ]
37.  Kakushima N, Fujishiro M, Kodashima S, Muraki Y, Tateishi A, Yahagi N, Omata M. Technical feasibility of endoscopic submucosal dissection for gastric neoplasms in the elderly Japanese population. J Gastroenterol Hepatol. 2007;22:311-314.  [PubMed]  [DOI]  [Cited in This Article: ]
38.  Tokioka S, Umegaki E, Murano M, Takeuchi N, Takeuchi T, Kawakami K, Yoda Y, Kojima Y, Higuchi K. Utility and problems of endoscopic submucosal dissection for early gastric cancer in elderly patients. J Gastroenterol Hepatol. 2012;27 Suppl 3:63-69.  [PubMed]  [DOI]  [Cited in This Article: ]
39.  Yang L, Fujimoto J, Qiu D, Sakamoto N. Trends in cancer mortality in the elderly in Japan, 1970-2007. Ann Oncol. 2010;21:389-396.  [PubMed]  [DOI]  [Cited in This Article: ]
40.  Yasunaga H, Horiguchi H, Kuwabara K, Matsuda S, Fushimi K, Hashimoto H, Ayanian JZ. Outcomes after laparoscopic or open distal gastrectomy for early-stage gastric cancer: a propensity-matched analysis. Ann Surg. 2013;257:640-646.  [PubMed]  [DOI]  [Cited in This Article: ]
41.  Kuwabara K, Matsuda S, Fushimi K, Ishikawa KB, Horiguchi H, Fujimori K, Yasunaga H, Miyata H. Quantitative assessment of the advantages of laparoscopic gastrectomy and the impact of volume-related hospital characteristics on resource use and outcomes of gastrectomy patients in Japan. Ann Surg. 2011;253:64-70.  [PubMed]  [DOI]  [Cited in This Article: ]
42.  Murata A, Okamoto K, Muramatsu K, Kubo T, Fujino Y, Matsuda S. Effects of additional laparoscopic cholecystectomy on outcomes of laparoscopic gastrectomy in patients with gastric cancer based on a national administrative database. J Surg Res. 2014;186:157-163.  [PubMed]  [DOI]  [Cited in This Article: ]
43.  Bernini M, Bencini L, Sacchetti R, Marchet A, Cristadoro L, Pacelli F, Berardi S, Doglietto GB, Rosa F, Verlato G. The Cholegas Study: safety of prophylactic cholecystectomy during gastrectomy for cancer: preliminary results of a multicentric randomized clinical trial. Gastric Cancer. 2013;16:370-376.  [PubMed]  [DOI]  [Cited in This Article: ]
44.  Lai SL, Yang JC, Wu JM, Lai IR, Chen CN, Lin MT, Lai HS. Combined cholecystectomy in gastric cancer surgery. Int J Surg. 2013;11:305-308.  [PubMed]  [DOI]  [Cited in This Article: ]
45.  Jeong IH, Choi SU, Lee SR, Kim JH, Park JM, Jin SH, Choi EK, Cho YK, Han SU. Outcomes after combined laparoscopic gastrectomy and laparoscopic cholecystectomy in gastric cancer patients. Eur Surg Res. 2009;42:203-208.  [PubMed]  [DOI]  [Cited in This Article: ]
46.  Kuwabara K, Matsuda S, Fushimi K, Ishikawa KB, Horiguchi H, Fujimori K. Hospital volume and quality of laparoscopic gastrectomy in Japan. Dig Surg. 2009;26:422-429.  [PubMed]  [DOI]  [Cited in This Article: ]
47.  Kuwabara K, Matsuda S, Fushimi K, Ishikawa KB, Horiguchi H, Fujimori K. Effect of hospital characteristics on the quality of laparoscopic gastrectomy in Japan. Gastroenterol Res. 2010;3:65-73.  [PubMed]  [DOI]  [Cited in This Article: ]
48.  Ryu M, Hamano M, Nakagawara A, Shinoda M, Shimizu H, Miura T, Yoshida I, Nemoto A, Yoshikawa A. The benchmark analysis of gastric, colorectal and rectal cancer pathways: toward establishing standardized clinical pathway in the cancer care. Jpn J Clin Oncol. 2011;41:2-9.  [PubMed]  [DOI]  [Cited in This Article: ]
49.  Nashimoto A, Akazawa K, Isobe Y, Miyashiro I, Katai H, Kodera Y, Tsujitani S, Seto Y, Furukawa H, Oda I. Gastric cancer treated in 2002 in Japan: 2009 annual report of the JGCA nationwide registry. Gastric Cancer. 2013;16:1-27.  [PubMed]  [DOI]  [Cited in This Article: ]
50.  Kenjo A, Miyata H, Gotoh M, Kitagawa Y, Shimada M, Baba H, Tomita N, Kimura W, Sugihara K, Mori M. Risk stratification of 7,732 hepatectomy cases in 2011 from the National Clinical Database for Japan. J Am Coll Surg. 2014;218:412-422.  [PubMed]  [DOI]  [Cited in This Article: ]
51.  Kimura W, Miyata H, Gotoh M, Hirai I, Kenjo A, Kitagawa Y, Shimada M, Baba H, Tomita N, Nakagoe T. A pancreaticoduodenectomy risk model derived from 8575 cases from a national single-race population (Japanese) using a web-based data entry system: the 30-day and in-hospital mortality rates for pancreaticoduodenectomy. Ann Surg. 2014;259:773-780.  [PubMed]  [DOI]  [Cited in This Article: ]
52.  Feuer EJ, Lee M, Mariotto AB, Cronin KA, Scoppa S, Penson DF, Hachey M, Cynkin L, Carter GA, Campbell D. The Cancer Survival Query System: making survival estimates from the Surveillance, Epidemiology, and End Results program more timely and relevant for recently diagnosed patients. Cancer. 2012;118:5652-5662.  [PubMed]  [DOI]  [Cited in This Article: ]