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ASSESSMENT OF PREOPERATIVE DIAGNOSTIC ACCURACY OF MULTIDETECTOR-ROW COMPUTED TOMOGRAPHY (MDCT) FOR RESECTABLE BILIARY CANCER: MULTI-INSTITUTIONAL VALIDITY STUDY IN JAPAN
Satoshi Nara^*25, Kazuaki Shimada²⁵, Katsuhiko Uesaka¹, Masaru Konishi², Masayuki Ohtsuka³, Satoshi Hirano⁴, Michiaki Unno⁵, Hiroaki Yanagimoto⁶, Tatsuya Nomura⁷, Naohiro Sata⁸, Hiroshi Wada⁹, Etsuro Hatano¹⁰, Hirohiko Sakamoto¹¹, Tetsuo Ohta¹², Yasuhiro Fujino¹³, Soichiro Morinaga¹⁴, Munenori Tahara¹⁵, Yoshiyasu Ambo¹⁶, Koji Ohta¹⁷, Tsutomu Fujii¹⁸, Hirofumi Shirakawa¹⁹, Hiroaki Nagano²⁰, Atsushi Miyamoto²¹, Kazuhisa Takeda²², Keishi Sugimachi²³, Junji Furuse^24
1Shizuoka Cancer Center Hospital, Shizuoka, Japan; ²National Cancer Center Hospital East, Kashiwa, Japan; ³Department of General Surgery, Chiba University, Chiba, Japan; ⁴Department of Gastroenterological Surgery II, Hokkaido University Graduate School of Medicine, Sapporo, Japan; ⁵Division of Hepato-Biliary-Pancreatic Surgery, Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan; ⁶Department of Surgery, Kansai Medical University, Hirakata, Japan; ⁷Department of Surgery, Niigata Cancer Centre Hospital, Niigata, Japan; ⁸Department of Surgery, Jichi Medical University, Shimono, Japan; ⁹Department of Surgery, Osaka International Cancer Institute, Osaka, Japan; ¹⁰Department of Surgery, Hyogo College of Medicine, Nishinomiya, Japan; ¹¹Saitama Cancer Center Hospital, Saitama, Japan; ¹²Department of Gastroenterologic Surgery, Kanazawa University, Kanazawa, Japan; ¹³Hyogo Prefectural Cancer Center, Akashi, Japan; ¹⁴Department of Hepato-Biliary and Pancreatic Surgery, Kanagawa Cancer Center, Yokohama, Japan; ¹⁵Sapporo Kosei Hospital, Sapporo, Japan; ¹⁶Teine Keijinkai Hospital, Sapporo, Japan; ¹⁷Shikoku Cancer Center, Matsuyama, Japan; ¹⁸Department of Surgery and Science, University of Toyama, Toyama, Japan; ¹⁹Tochigi Cancer Center, Utsunomiya, Japan; ²⁰Division of Hepato-Biliary-Pancreatic Surgery and liver transplantation, Yamaguchi University Hospital, Yamaguchi, Japan; ²¹National Hospital Organization Osaka National Hospital, Osaka, Japan; ²²Yokohama City University Medical Center, Yokohama, Japan; ²³Kyushu Cancer Center, Fukuoka, Japan; ²⁴Department of Medical Oncology, Kyorin University, Mitaka, Japan; ²⁵Hepatobiliary and Pancreatic Surgery Division, National Cancer Center Hospital, Tokyo, Japan

Background: Multidetector-row computed tomography (MDCT) is recommended as a standard preoperative examination for resectable biliary cancer. However, its diagnostic accuracy has not been well established. Hepatobiliary and Pancreatic Oncology Group (HBPOG) of the Japan Clinical Oncology Group (JCOG) conducted a multi-institutional retrospective study to validate the accuracy of MDCT diagnosis before initiating a future clinical trial of preoperative therapy for resectable biliary cancer. The aim of the study was to investigate the risk of overdiagnosis through which patients with early stage disease may receive unnecessary preoperative therapy (UMIN000030917).
Patients and methods: We retrospectively reviewed the records of 1,237 patients who underwent surgery for biliary cancer at 24 Japanese hospitals between 2014 and 2016. All patients underwent preoperative MDCT (slice ≤5mm) within 60 days prior to surgery. Based on the data of the biliary and liver cancer registry in Japan, candidates of the preoperative therapy trial were defined as stage II-IVA for perihilar cholangiocarcinoma, stage IB-III for distal cholangiocarcinoma, stage IIIA-IVA for gallbladder carcinoma, stage IIA-III for ampullary carcinoma, and stage III-IVA for intrahepatic cholangiocarcinoma according to Japanese classification of biliary tract cancers (6th edition) and primary liver cancers (6th edition). The primary endpoint was the proportion of pathological stage I (stage IA for distal cholangiocarcinoma) patients who were diagnosed by MDCT with a biliary cancer that fulfilled the inclusion criteria of the preoperative therapy trial, which we predicted to be ≤10% for ampullary carcinoma, and ≤5% for others. The secondary endpoints were sensitivity and specificity of MDCT to diagnose: 1) A biliary tract cancer that pathologically fulfilled the inclusion criteria of preoperative therapy trial; 2) lymph node metastasis; and 3) R1 (invasive cancer) or R2 resection.
Results: The number of analyzed patients with perihilar, distal, gallbladder, ampullary and intrahepatic (cholangio-) carcinomas were 298, 355, 190, 201, and 128, respectively. The primary endpoints were 5.4%, 4.0%, 2.2%, 39.3%, and 3.1% in perihilar, distal, gallbladder, ampullary and intrahepatic (cholangio-) carcinomas, respectively. Diagnostic accuracy was not significantly improved even in patients with MDCT slices of 1 mm or less. The secondary endpoints are shown in Table 1.
Conclusion: The accuracy of MDCT was validated in patients with perihilar, distal, gallbladder, and intrahepatic (cholangio-) carcinoma, but not in patients with ampullary carcinoma. Additional examinations other than MDCT may be necessary to improve diagnostic accuracy for ampullary carcinoma.

Secondary endpoints

	Perihilar cholangiocarcinoma	Distal cholangiocarcinoma	Gallbladder carcinoma	Ampullary carcinoma	Intrahepatic cholangiocarcinoma
Sensitivity of MDCT to diagnose a biliary cancer that pathologically fulfilled the inclusion criteria of the preoperative therapy trial	0.987	0.931	0.575	0.493	0.780
Specificity of MDCT to diagnose a biliary cancer that pathologically fulfilled the inclusion criteria of the preoperative therapy trial	0.143	0.326	0.941	0.786	0.306
Sensitivity of MDCT to diagnose lymph node metastasis	0.307	0.255	0.403	0.266	0.378
Specificity of MDCT to diagnose lymph node metastasis	0.861	0.836	0.942	0.926	0.904
Sensitivity of MDCT to diagnose R1 (invasive cancer) or R2 resection	0.197	0.231	0.130	0.500	0
Specificity of MDCT to diagnose R1 (invasive cancer) or R2 resection	0.916	0.988	0.994	1.0	0.991

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