Verifying the M1c category of CRC: analysis of the data from a Japanese multi-institutional database
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In the TNM classification 8th edition, colorectal cancer (CRC) with peritoneal metastasis, one of the most poor prognostic factors, is classified as M1c (stage IVC), regardless of the presence/absence of other distant metastasis. Several cases with peritoneal metastasis have been successfully managed by surgical treatment; therefore, there is need to give more consideration for uniform differentiation of peritoneal metastasis. This study was aimed at verifying the classification of M1c in CRC.
Materials and methods
Data from a multi-institutional retrospective cohort of 2929 CRC patients who were diagnosed as having stage IV CRC from 1997 to 2007 were analyzed. Peritoneal metastasis alone was defined as M1c1 and peritoneal metastasis with other organ metastasis was defined as M1c2.
The 3-year OS of patients with M1c1 was significantly higher than that of patients with M1b (25.6% vs. 18.1%; HR 0.77; 95% confidence interval (CI) 0.65–0.92; p = 0.005); in particular, the prognosis of patients with M1c1 with localized peritoneal metastasis and R0 resection was equivalent to that of patients with M1a (3-year OS 40.5% vs. 39.2%, p = 0.41). On the other hand, among the stage IV cases, patients with M1c2 had a low R0 resection rate (5.9%) and the worst prognosis (3-year OS, 9.1%).
The prognosis of M1c1 with localized peritoneal metastasis is relatively good, and can be further improved by surgical intervention. Combined evaluation of the M1c1/2 classification with the peritoneal metastasis grade may help in establishing more individualized treatment strategies.
KeywordsColorectal cancer Peritoneal metastasis TNM staging system Stage IVC
The authors completed this study in collaboration with the following: M. Watanabe (Kitasato University School of Medicine), I. Takemasa (Sapporo Medical University), K. Hakamada (Hirosaki University), H. Kameyama (Niigata University), H. Ueno (National Defense Medical college), S. Ishihara (Tokyo University), K. Takahashi (Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital), Y. Kanemitsu (National Cancer Center Hospital), M. Itabashi (Tokyo Women’s Medical University), T. Kiyomatsu (National Center for Global Health and Medicine), Y. Kinugasa (Tokyo Medical and Dental University), K. Okabayashi (Keio University), Y. Hashiguchi (Teikyo University), T. Masaki (Kyorin University), K. Hanai (Fujita Health University), K. Komori (Aichi Cancer Center Hospital), Y. Sakai (Kyoto University), M. Ohue (Osaka Medical Center for Cancer and Cardiovascular Diseases), N. Tomita (Hyogo College of Medicine), and Y. Akagi (Kurume University).
Compliance with ethical standards
This study was conducted in accordance with the Declaration of Helsinki and with the approval of the Research Ethics Committee of Tochigi Cancer Center. Informed consent for this research was substituted by a consent form at each of the participant’s institutes, because of the retrospective study design.
Conflict of interest
The authors declare that they have no conflict of interest.
Ethics approval was obtained from the Tochigi Cancer Center’s institutional review board, and for this type of study, formal consent is not required.
- 1.Brierley JDGM, Wittekind C (eds) (2016) TNM classification of malignant tumours, 8th edn. John Wiley & Sons, HobokenGoogle Scholar
- 7.Rectum JSfCotCa (2018) Japanese classification of colorectal, appendiceal, and anal carcinoma 9th edn. Kanehara & Co., Ltd., TokyoGoogle Scholar
- 10.Shida D, Kanemitsu Y, Hamaguchi T, Shimada Y (2019) Introducing the eighth edition of the tumor-node-metastasis classification as relevant to colorectal cancer, anal cancer and appendiceal cancer: a comparison study with the seventh edition of the tumor-node-metastasis and the Japanese Classification of Colorectal, Appendiceal, and Anal Carcinoma. Jpn J Clin Oncol 1;49(4):321–328CrossRefGoogle Scholar
- 16.Loupakis F, Yang D, Yau L, Feng S, Cremolini C, et al. (2015) Primary tumor location as a prognostic factor in metastatic colorectal cancer. J Natl Cancer Inst 107(3). https://doi.org/10.1093/jnci/dju427