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Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Surg. Dec 27, 2021; 13(12): 1567-1583
Published online Dec 27, 2021. doi: 10.4240/wjgs.v13.i12.1567
Mucinous adenocarcinoma: A unique clinicopathological subtype in colorectal cancer
An Huang, Yong Yang, Jing-Yi Shi, Yu-Kun Li, Jing-Xuan Xu, Yu Cheng, Jin Gu
An Huang, Yong Yang, Jing-Yi Shi, Yu-Kun Li, Jing-Xuan Xu, Yu Cheng, Jin Gu, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Gastrointestinal Surgery III, Peking University Cancer Hospital & Institute, Beijing 100142, China
Jin Gu, Peking-Tsinghua Center for Life Science, Peking University International Cancer Center, Beijing 100142, China
Jin Gu, Department of Gastrointestinal Surgery, Peking University Shougang Hospital, Beijing 100144, China
Author contributions: Gu J contributed to conceptualization; Huang A, Li YK and Xu JX contributed to literature search and data analysis; Huang A wrote original draft preparation; Yang Y, Shi JY, Cheng Y reviewed and edited manuscript; Gu J supervised manuscript.
Supported by the Beijing Municipal Science & Technology Commission, Clinical Application and Development of Capital Characteristic, No. Z171100001017087.
Conflict-of-interest statement: Authors declare no conflict of interests for this article.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (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: Jin Gu, FACS, FASCRS, MD, Professor, Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education/Beijing), Department of Gastrointestinal Surgery III, Peking University Cancer Hospital & Institute, No. 52 Fucheng Rd, Haidian District, Beijing 100142, China. zlguj@bjmu.edu.cn
Received: May 29, 2021
Peer-review started: May 29, 2021
First decision: June 23, 2021
Revised: July 2, 2021
Accepted: August 30, 2021
Article in press: August 30, 2021
Published online: December 27, 2021
Abstract

Mucinous adenocarcinoma (MAC) is a unique clinicopathological subtype of colorectal cancer, which is characterized by extracellular mucinous components that comprise at least 50% of the tumor tissue. The clinical characteristics, molecular features, response to chemo-/radiotherapy, and prognosis of MAC are different from that of non-MAC (NMAC). MAC is more common in the proximal colon, with larger volume, higher T-stage, a higher proportion of positive lymph nodes, poorer tumor differentiation, and a higher proportion of peritoneal implants compared to NMAC. Although biopsy is the main diagnostic method for MAC, magnetic resonance imaging is superior in accuracy, especially for rectal carcinoma. The aberrant expression of mucins, including MUC1, MUC2 and MUC5AC, is a notable feature of MAC, which may be related to tumor invasion, metastasis, inhibition of apoptosis, and chemo-/radiotherapy resistance. The genetic origin of MAC is mainly related to BRAF mutation, microsatellite instability, and the CpG island methylator phenotype pathway. In addition, the poor prognosis of rectal MAC has been confirmed by various studies, and that of colonic MAC is still controversial. In this review, we summarize the epidemiology, clinicopathological characteristics, molecular features, methods of diagnosis, and treatments of MAC in order to provide references for further fundamental and clinical research.

Keywords: Mucinous adenocarcinoma, Colorectal cancer, Mucin, Microsatellite instability, Magnetic resonance imaging, Treatment

Core tip: Colorectal mucinous adenocarcinoma (MAC) is a unique clinicopathological subtype in colorectal cancer. MAC exhibits a higher frequency of microsatellite instability, higher CpG island methylator phenotype of high degree, higher frequency of BRAF and KRAS gene mutations, and lower frequency of TP53 mutations. One of the most important features of MAC is the aberrant expression of a large number of mucins, including MUC1, MUC2 and MUC5AC. We discuss the epidemiology, clinicopathological characteristics, molecular features, methods of diagnosis, and treatments of MAC in order to provide references for further fundamental and clinical research.