Comparison of model fit and discriminatory ability of M category as defined by the 7th and 8th editions of the tumor‐node‐metastasis classification of colorectal cancer and the 9th edition of the Japanese classification. (29th September 2021)

• Record Type: Journal Article
• Authors: Shida, Dai; Boku, Narikazu; Nakamura, Yuya; Yoshida, Takefumi; Tanabe, Taro; Yasui, Kohei; Takashima, Atsuo; Kanemitsu, Yukihide
• Is Part Of: Cancer medicine. Volume 10:Number 20(2021)
• Page Start: 6937
• Page End: 6946
• Publication Date: 2021-09-29
• Subjects: anal carcinoma -- appendiceal -- colorectal cancer -- japanese Classification of colorectal -- TNM 7th edition -- TNM 8th edition; 616.994005
• DOI: 10.1002/cam4.3972
• Languages: English
• ISSNs: 2045-7634

Abstract

ABSTRACT: Background: In transitioning from the 7th edition of the tumor‐node‐metastasis classification (TNM‐7) to the 8th edition (TNM‐8), colorectal cancer with peritoneal metastasis was newly categorized as M1c. In the 9th edition of the Japanese Classification of colorectal, appendiceal, and anal carcinoma (JPC‐9), M1c is further subdivided into M1c1 (without other organ involvement) and M1c2 (with other organ involvement). This study aimed to compare the model fit and discriminatory ability of the M category of these three classification systems, as no study to date has made this comparison. Methods: The study population consisted of stage IV colorectal cancer patients who were referred to the National Cancer Center Hospital from 2000 to 2017. The Akaike information criterion (AIC), Harrell's concordance index (C‐index), and time‐dependent receiver operating characteristic (ROC) curves were used to compare the three classification systems. Subgroup analyses, stratified by initial treatment year, were also performed. Results: According to TNM‐8, 670 (55%) patients had M1a, 273 (22%) had M1b, and 279 (23%) had M1c (87 M1c1 and 192 M1c2 using JPC‐9) tumors. Among the three classification systems, JPC‐9 had the lowest AIC value (JPC‐9: 10546.3; TNM‐7: 10555.9; TNM‐8: 10585.5), highest C‐index (JPC‐9: 0.608; TNM‐7: 0.598; TNM‐8: 0.599), and superior time‐dependent ROC curves throughout the observation period. Subgroup analyses were consistent with these results. Conclusions: While the revised M category definition did not improve model fit and discriminatory ability from TNM‐7 to TNM‐8, further subdivision of M1c in JPC‐9 improved these parameters. These results support further revisions to M1 subcategories in future editions of the TNM classification system. Abstract : In transitioning from the TNM 7th edition to the TNM 8th edition, colorectal cancer with peritoneal metastasis was newly categorized as M1c, and in the Japanese Classification (9th edition), M1c is further subdivided into M1c1 (without other organ involvement) and M1c2 (with other organ involvement). To date, no study has compared the model fit and discriminatory ability of the M category of these three classification systems. In this study, with 1222 consecutive stage IV colorectal cancer patients, we clearly demonstrated that, by comparing AIC, Harrell's c‐index, and time‐dependent ROC curves between the three classification systems, while the revised M category definition did not improve model fit and discriminatory ability from TNM 7th edition to the TNM 8th edition, further subdivision of M1c in the Japanese Classification improved these parameters.