J Cancer 2021; 12(11):3299-3306. doi:10.7150/jca.55097

Research Paper

A Novel TNM Classification for Colorectal Cancers based on the Metro-ticket Paradigm

Jun-Peng Pei1#, Chun-Dong Zhang1,2#, Xiang Fu1, Yong Ba1, Shuai Yue1, Zhe-Ming Zhao1, Dong-Qiu Dai1,3✉

1. Department of Gastrointestinal Surgery, The Fourth Affiliated Hospital of China Medical University, Shenyang 110032, China.
2. Department of Gastrointestinal Surgery, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
3. Cancer Center, The Fourth Affiliated Hospital of China Medical University, Shenyang 110032, China.
#Co-first authors with equal contributions to this work.

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Citation:
Pei JP, Zhang CD, Fu X, Ba Y, Yue S, Zhao ZM, Dai DQ. A Novel TNM Classification for Colorectal Cancers based on the Metro-ticket Paradigm. J Cancer 2021; 12(11):3299-3306. doi:10.7150/jca.55097. Available from https://www.jcancer.org/v12p3299.htm

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Abstract

Background: Several revisions of the TNM classifications for colorectal cancer (CRC) have acknowledged that the oncological outcomes of stage IIB/IIC CRC are worse than those of stage IIIA. We aimed to develop a novel TNM (nTNM) classification based on the metro-ticket paradigm.

Methods: We identified eligible CRC patients from the Surveillance, Epidemiology, and End Results database. The nTNM was developed using distance from the origin on a Cartesian plane incorporating the pN (x-axis) and pT (y-axis) stages, and was compared with the AJCC TNM classification. The areas under the curves (AUCs), calibration curves, and Akaike's information criterion (AIC) were used to evaluate the predictive performances of the two classifications. Clinical benefits were further estimated by decision curve analyses. The validation cohort was applied to validate these findings.

Results: A total of 58,192 CRC patients (40,736 training cohort, 17,456 validation cohort) were finally included. In the training cohort, 18,476 patients (45.4%) experienced upstaging and 15,907 patients (39.0%) experienced downstaging in the nTNM classification compared with the TNM classification. Taking the prognosis of stage I as the reference, survival decreased with increasing nTNM stage. The nTNM classification showed better discrimination (AUC, 0.678 vs. 0.667, P<0.001), model-fitting (AIC, 236,525 vs. 237,741), and clinical benefits than the TNM classification. Similar results were found in the validation cohort.

Conclusions: The nTNM classification for CRC has better predictive performances and superior accuracy for predicting prognosis compared with the TNM classification. The nTNM classification should therefore be considered in future revisions of the TNM classification.

Keywords: colorectal cancer, TNM classification, metro-ticket, novel TNM classification