Retrospective Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 28, 2015; 21(24): 7514-7521
Published online Jun 28, 2015. doi: 10.3748/wjg.v21.i24.7514
Lymph node ratio-based staging system for esophageal squamous cell carcinoma
Shao-Bin Chen, Hong-Rui Weng, Geng Wang, Xiao-Fang Zou, Di-Tian Liu, Yu-Ping Chen, Hao Zhang
Shao-Bin Chen, Hong-Rui Weng, Geng Wang, Di-Tian Liu, Yu-Ping Chen, Department of Thoracic Surgery, Cancer Hospital of Shantou University Medical College, Shantou 515031, Guangdong Province, China
Xiao-Fang Zou, Hao Zhang, Cancer Research Centre, Shantou University Medical College, Shantou 515031, Guangdong Province, China
Xiao-Fang Zou, Department of Medical Oncology, People’s Hospital of Meizhou City, Affiliated Meizhou Hospital of Sun Yat-sen University, Meizhou 514000, Guangdong Province, China
Hao Zhang, Departments of Integrative Oncology, Cancer Hospital of Shantou University Medical College, Shantou 515031, Guangdong Province, China
Author contributions: Chen SB and Weng HR contributed equally to this work; Chen YP designed the research; Chen SB, Weng HR, Wang G, Yang JS, Yang WP, Liu DT and Zhang H performed the research; Chen SB and Zou XF analyzed the data; Chen SB and Weng HR wrote the paper.
Ethics approval: The study was reviewed and approved by the Cancer Hospital of Shantou University Medical College Institutional Review Board.
Conflict-of-interest: All authors declare no conflicts of interest.
Data sharing: Technical appendix, statistical code, and dataset available from the corresponding author at stchenyp@hotmail.com
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Yu-Ping Chen, Professor, Department of Thoracic Surgery, Cancer Hospital of Shantou University Medical College, No. 7 Raoping Road, Shantou 515000, Guangdong Province, China. stchenyp@hotmail.com
Telephone: +86-754-88555844 Fax: +86-754-88560352
Received: November 15, 2014
Peer-review started: November 17, 2014
First decision: December 26, 2014
Revised: February 6, 2015
Accepted: March 18, 2015
Article in press: March 19, 2015
Published online: June 28, 2015
Processing time: 225 Days and 16.9 Hours
Abstract

AIM: To analyze a modified staging system utilizing lymph node ratio (LNR) in patients with esophageal squamous cell carcinoma (ESCC).

METHODS: Clinical data of 2011 patients with ESCC who underwent surgical resection alone between January 1995 and June 2010 at the Cancer Hospital of Shantou University Medical College were reviewed. The LNR, or node ratio (Nr) was defined as the ratio of metastatic LNs ompared to the total number of resected LNs. Overall survival between groups was compared with the log-rank test. The cutoff point of LNR was established by grouping patients with 10% increment in Nr, and then combining the neighborhood survival curves using the log-rank test. A new TNrM staging system, was constructed by replacing the American Joint Committee on Cancer (AJCC) N categories with the Nr categories in the new TNM staging system. The time-dependent receiver operating characteristic curves were used to evaluate the predictive performance of the seventh edition AJCC staging system and the TNrM staging system.

RESULTS: The median number of resected LNs was 12 (range: 4-44), and 25% and 75% interquartile rangeswere8 and 16. Patients were classified into four Nr categories with distinctive survival differences (Nr0: LNR = 0; Nr1: 0% < LNR ≤ 10%; Nr2: 10% < LNR ≤ 20%; and Nr3: LNR > 20%). From N categories to Nr categories, 557 patients changed their LN stage. The median survival time (MST) for the four Nr categories (Nr0-Nr3) was 155.0 mo, 39.0 mo, 28.0 mo, and 19.0 mo, respectively, and the 5-year overall survival was 61.1%, 41.1%, 33.0%, and 22.9%, respectively (P < 0.001). Overall survival was significantly different for the AJCC N categories when patients were subgrouped into 15 or more vs fewer than 15 examined nodes, except for the N3 category (P = 0.292). However, overall survival was similar when the patients in all four Nr categories were subgrouped into 15 or more vs fewer than 15 nodes. Using the time-dependent receiver operating characteristic, we found that the Nr category and TNrM stage had higher accuracy in predicting survival than the AJCC N category and TNM stage.

CONCLUSION: A staging system based on LNR may have better prognostic stratification of patients with ESCC than the current TNM system, especially for those undergoing limited lymphadenectomy.

Keywords: Cancer staging; Esophagectomy; Esophageal squamous cell carcinoma; Lymph node ratio; Prognosis

Core tip: The lymph node ratio (LNR) or node ratio (Nr) is an independent prognostic factor in esophageal cancer patients. In the current study, we evaluated an LNR-based staging system in patients with esophageal squamous cell carcinoma (ESCC) and compared it with the seventh edition American Joint Committee on Cancer (AJCC) staging system. We propose optimal Nr categories for ESCC, and demonstrated that a TNrM staging system bases on LNR may have better prognostic stratification of patients than the AJCC staging system. The application of this new staging system may aid oncologists in improved prediction of prognosis.