A novel TNM staging system for gastric cancer based on the metro-ticket paradigm: a comparative study with the AJCC-TNM staging system
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The metro-ticket prognostic tool for hepatocellular carcinoma has been proven to predict outcome, but a similar concept has not been investigated for GC. The objective of the current study was to apply the principles of the metro-ticket paradigm to develop a novel TNM staging system (nTNM) for gastric cancer (GC).
The nTNM considered the distance from the origin on a Cartesian plane incorporating the pN (x-axis) and pT (y-axis) stages. GC patients undergoing radical resection at Fujian Medical University Union Hospital (FMUUH) (n = 4267) were included. The nTNM was validated using 2 external cohorts from the Sun Yat-sen University Cancer Center (SYSUCC) (n = 1800) and Surveillance, Epidemiology, and End Results (SEER) (n = 3227) databases.
nTNM classes with the same distance from the origin have same stage; the stage increases with this distance. Among all patients, 48.0% (n = 2049) were restaged in the nTNM compared with the 7th edition of the AJCC-TNM classification; 26.2% (n = 1116) were downstaged in the nTNM compared with the 8th edition. The nTNM provides significant survival differences between stages (all P < 0.001). The survival difference between stages IB and IIA was especially large for the nTNM (P < 0.001) compared to the 7th and 8th editions (P = 0.073). The concordance index and hazard ratio increased successively with the nTNM stage. Similar findings were observed in both external cohorts.
Compared with the AJCC-TNM classification, the nTNM for GC is easier to remember and provides some improvements; therefore, the nTNM may be considered for adoption in future editions of the AJCC-TNM classification.
KeywordsGastric cancer AJCC TNM staging system Metro-ticket
This study was funded by the Scientific and Technological Innovation Joint Capital Projects of Fujian Province (2016Y9031), Construction Project of Fujian Province Minimally Invasive Medical Center (No. 171), the second batch of special support funds for Fujian Province Innovation and Entrepreneurship Talents (2016B013), Youth Scientific Research Subject of Fujian Provincial Health and Family Planning Commission (No. 2015-1-37), QIHANG funds of Fujian Medical University (No.2016QH025), and Joint Health Programs of the Provincial Natural Foundation (2015J01464).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Human rights statement and informed consent
All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later versions. Informed consent or substitute for it was obtained from all patients for being included in the study.
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