Observational Study
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World J Gastroenterol. May 7, 2014; 20(17): 5104-5112
Published online May 7, 2014. doi: 10.3748/wjg.v20.i17.5104
TNM staging of colorectal cancer should be reconsidered by T stage weighting
Jun Li, Bao-Cai Guo, Li-Rong Sun, Jian-Wei Wang, Xian-Hua Fu, Su-Zhan Zhang, Graeme Poston, Ke-Feng Ding
Jun Li, Jian-Wei Wang, Xian-Hua Fu, Su-Zhan Zhang, Ke-Feng Ding, Department of Surgical Oncology, Second Affiliated Hospital, and The Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Zhejiang University College of Medicine, Hangzhou 310009, Zhejiang Province, China
Bao-Cai Guo, Li-Rong Sun, Department of Applied Mathematics, School of Statistics and Mathematics, Zhejiang Gongshang University, Xiasha University Town, Hangzhou 310018, Zhejiang Province, China
Graeme Poston, Department of Surgery, Aintree University Hospital, Liverpool L9 7AL, United Kingdom
Author contributions: Li J and Ding KF raised doubts about the relationship between the 7th edition of the AJCC TNM staging system and the survival of patients with colorectal cancer, and designed the methods, proposed the revised TNM staging system, and wrote the draft of the manuscript; Guo BC and Sun LR undertook the statistical analysis; Wang JW, Fu XH, Zhang SZ and Poston G discussed the hypothesis that the T stage has greater weight in affecting the survival of colorectal cancer patients and took part in the decision-making process for rearranging the TNM staging system and also participated in the study design and revision of the manuscript; all authors have read, revised, and approved the manuscript.
Correspondence to: Ke-Feng Ding, Professor, Department of Surgical Oncology, Second Affiliated Hospital, and The Key Laboratory of Cancer Prevention and Intervention, China National Ministry of Education, Zhejiang University College of Medicine, No. 88 Jiefang Road, Hangzhou 310009, Zhejiang Province, China. dingkefeng@zju.edu.cn
Telephone: +86-571-87784760 Fax: +86-571-87783458
Received: October 31, 2013
Revised: February 10, 2014
Accepted: March 4, 2014
Published online: May 7, 2014
Processing time: 187 Days and 13.8 Hours
Abstract

AIM: To verify that the T stage has greater weight than the N stage in the staging of colorectal cancer.

METHODS: Open data from the Surveillance, Epidemiology, and End Results program were reviewed and analyzed according to the T stage, N stage, and patients’ observed survival (OS). The relative weights of the T and N stages were calculated by multiple linear regressions based on their impact on survival. Risk scores for 25 TN categories were then calculated from the T and N stage relative weights, and a rearranged tumor node metastasis (TNM) staging system was proposed via a cluster analysis of the TN scores.

RESULTS: Both T and N stages significantly affect the OS of patients with colorectal cancer. Moreover, the T stage has greater weight than the N stage in the TNM staging system of colorectal cancer. For colon cancer, the relative T and N stage weights were 0.58 and 0.42, respectively, and for rectal cancer, the relative T and N stage weights were 0.61 and 0.39, respectively. On the basis of cluster analysis of the TN scores, T1N1a was classified to stage I, and T2N1a-1b and T1N1b-2a were classified to stage II in our revised TNM staging system for both colon and rectal cancer. For colon cancer, T4bN0 was classified to stage IIIa, but for rectal cancer, it was classified to stage IIIb.

CONCLUSION: As the T stage affects colorectal cancer survival more significantly than the N stage, the TNM staging should be revised by relative T stage weight.

Keywords: Colorectal cancer; Neoplasm staging; Cluster analysis; Survival analysis; Observational study

Core tip: The 7th edition of the American Joint Committee on Cancer (AJCC) tumor node metastasis (TNM) staging system for colorectal cancer can not predict survival linearly by stage. We propose that the T stage has greater weight than the N stage, more especially in rectal cancer than in colon cancer. Moreover, in this article, we propose a revised scheme for the 7th edition of the AJCC TNM staging system. In our revised scheme, T4bN0 is classified to stage IIIa in colon cancer, but to stage IIIb in rectal cancer. This is the first attempt to revise the established TNM staging system for colorectal cancer by shaking the keystone of present classification based on the lymph nodes status.