Retrospective Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Nov 28, 2019; 25(44): 6541-6550
Published online Nov 28, 2019. doi: 10.3748/wjg.v25.i44.6541
Cystic duct cancer: Should it be deemed as a type of gallbladder cancer?
Tu-Nan Yu, Ying-Ying Mao, Fang-Qiang Wei, Hui Liu
Tu-Nan Yu, Department of General Surgery, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, Zhejiang Province, China
Ying-Ying Mao, Department of Epidemiology and Biostatistics, Zhejiang Chinese Medical University, Hangzhou 310053, Zhejiang Province, China
Fang-Qiang Wei, Department of Hepatobiliary and Pancreatic Surgery, Zhejiang Provincial People’s Hospital, Hangzhou Medical College, Hangzhou 310014, Zhejiang Province, China
Hui Liu, Zhejiang Provincial Key Laboratory of Laparoscopic Technology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, Zhejiang Province, China
Author contributions: Mao YY, Wei FQ and Liu H designed the research; Yu TN, Mao YY, Wei FQ and Liu H performed the research; Yu TN and Liu H analyzed the data; Yu TN, Mao YY, Wei FQ and Liu H wrote the paper.
Supported by Zhejiang Provincial Natural Science Foundation of China, No. LQ17H030003.
Institutional review board statement: The data in this study was obtained from the SEER database and the National Cancer Institute had given us permission to access data for researching (Reference number: 10536-Nov2017). Given that SEER data is de-identified and ethics approval is waived, this study was exempted from Institutional Research Board review.
Informed consent statement: Patients were not required to give informed consent to the study because the analysis used anonymous clinical data that are publicly available from the SEER database.
Conflict-of-interest statement: All authors declare no conflicts of interest related to this article.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Hui Liu, PhD, Research Assistant Professor, Zhejiang Provincial Key Laboratory of Laparoscopic Technology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310016, Zhejiang Province, China. lhui2010@zju.edu.cn
Telephone: +86-571-86006653 Fax: +86-571-86006653
Received: August 16, 2019
Peer-review started: August 16, 2019
First decision: October 14, 2019
Revised: October 24, 2019
Accepted: November 13, 2019
Article in press: November 13, 2019
Published online: November 28, 2019
Abstract
BACKGROUND

According to the latest American Joint Committee on Cancer and Union for International Cancer Control manuals, cystic duct cancer (CC) is categorized as a type of gallbladder cancer (GC), which has the worst prognosis among all types of biliary cancers. We hypothesized that this categorization could be verified by using taxonomic methods.

AIM

To investigate the categorization of CC based on population-level data.

METHODS

Cases of biliary cancers were identified from the Surveillance, Epidemiology, and End Results 18 registries database. Together with routinely used statistical methods, three taxonomic methods, including Fisher’s discriminant, binary logistics and artificial neuron network (ANN) models, were used to clarify the categorizing problem of CC.

RESULTS

The T staging system of perihilar cholangiocarcinoma [a type of extrahepatic cholangiocarcinoma (EC)] better discriminated CC prognosis than that of GC. After adjusting other covariates, the hazard ratio of CC tended to be closer to that of EC, although not reaching statistical significance. To differentiate EC from GC, three taxonomic models were built and all showed good accuracies. The ANN model had an area under the receiver operating characteristic curve of 0.902. Using the three models, the majority (75.0%-77.8%) of CC cases were categorized as EC.

CONCLUSION

Our study suggested that CC should be categorized as a type of EC, not GC. Aggressive surgical attitude might be considered in CC cases, to see whether long-term prognosis could be immensely improved like the situation in EC.

Keywords: Cystic duct cancer, Gallbladder cancer, Extrahepatic cholangiocarcinoma, Surgical management, Taxonomy, Categorization

Core tip: In the latest American Joint Committee on Cancer and Union for International Cancer Control manuals, cystic duct cancer (CC) is categorized as a type of gallbladder cancer, yet not verified by direct epidemiological evidence in previous studies. Our study used taxonomic methods to analyze population-based big data, including Fisher’s discriminant, binary logistics and artificial neuron network models. By using these three models, our study proved that CC is better to be deemed and treated as a kind of extrahepatic cholangiocarcinoma.