Retrospective Cohort Study
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. May 26, 2021; 9(15): 3531-3545
Published online May 26, 2021. doi: 10.12998/wjcc.v9.i15.3531
Critical prognostic value of the log odds of negative lymph nodes/tumor size in rectal cancer patients
Jie-Bin Xie, Yue-Shan Pang, Xun Li, Xiao-Ting Wu
Jie-Bin Xie, Xiao-Ting Wu, Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, Chengdu 610041, Sichuan Province, China
Jie-Bin Xie, Xun Li, Department of Gastrointestinal Surgery, Affiliated Hospital of North Sichuan Medical College China, Nanchong 637200, Sichuan Province, China
Yue-Shan Pang, Department of Geriatrics, The Second Clinical Medical College of North Sichuan Medical College, Nanchong Central Hospital, Nanchong 637200, Sichuan Province, China
Author contributions: Xie JB performed design, data collection, analysis, and drafting of manuscript; Pang YS performed design, data collection, and analysis; Li X performed design, data collection, and review; Wu XT performed design, analysis, review and editing; all authors read and approved the final version of the manuscript.
Supported by Cooperative Fund of Nanchong Government and North Sichuan Medical College, No. 18SXHZ0357.
Institutional review board statement: This study was exempted from Institutional Review Board approval, in view of the SEER’s use of unidentifiable patient information. Due to the strict register-based nature of the study, informed consent was waived. We also received permission to obtain research data from the SEER database, No. 11112-Nov2019.
Informed consent statement: Patients were not required to provide informed consent for the study because the analysis used anonymous clinical data.
Conflict-of-interest statement: The authors declare that they have no conflict of interest.
Data sharing statement: No additional data are available.
STROBE statement: The authors have read the STROBE Statement-checklist of items, and the manuscript was prepared and revised according to the STROBE Statement-checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (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/
Corresponding author: Xiao-Ting Wu, MD, PhD, Chief Doctor, Department of Gastrointestinal Surgery, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Wuhou District, Chengdu 610041, Sichuan Province, China. wxt1@medmail.com.cn
Received: November 12, 2020
Peer-review started: November 12, 2020
First decision: December 24, 2020
Revised: January 2, 2021
Accepted: March 10, 2021
Article in press: March 10, 2021
Published online: May 26, 2021
Processing time: 180 Days and 6.7 Hours
Abstract
BACKGROUND

The number of negative lymph nodes (NLNs) and tumor size are associated with prognosis in rectal cancer patients undergoing surgical resection. However, little is known about the prognostic significance of the NLN count after adjusting for tumor size.

AIM

To assess the prognostic impact of the log odds of NLN/tumor size (LONS) in rectal cancer patients.

METHODS

Data of patients with stage I–III rectal cancer were extracted from the Surveillance, Epidemiology, and End Results Program database. These patients were randomly divided into a training cohort and a validation cohort. Univariate and multivariate Cox regression analyses were used to determine the prognostic value of the LONS. The optimal cutoff values of LONS were calculated using the "X-tile" program. Stratified analysis of the effect of LONS on cancer-specific survival (CSS) and overall survival (OS) were performed. The Kaplan-Meier method with the log-rank test was used to plot the survival curve and compare the survival data among the different groups.

RESULTS

In all, 41080 patients who met the inclusion criteria were randomly divided into a training cohort (n = 28775, 70%) and a validation cohort (n = 12325, 30%). Univariate and multivariate analyses identified the continuous variable LONS as an independent prognostic factor for CSS [training cohort: Hazard ratio (HR) = 0.47, 95% confidence interval (CI): 0.44–0.51, P < 0.001; validation cohort: HR = 0.46, 95%CI: 0.41-0.52, P < 0.001] and OS (training cohort: HR = 0.53, 95%CI: 0.49-0.56, P < 0.001; validation cohort: HR = 0.52, 95%CI: 0.42-0.52, P < 0.001). The X-tile program indicated that the difference in CSS was the most significant for LONS of -0.8, and the cutoff value of -0.4 can further distinguish patients with a better prognosis in the high LONS group. Stratified analysis of the effect of the categorical variable LONS on CSS and OS revealed that LONS was also an independent predictor, independent of pN stage, pT stage, tumor-node-metastasis stage, site, age, sex, the number of examined lymph nodes, race, preoperative radiotherapy and carcinoembryonic antigen level.

CONCLUSION

LONS is associated with improved survival of rectal cancer patients independent of other clinicopathological factors.

Keywords: Rectal cancer; Negative lymph nodes; Negative lymph nodes/tumor size; Prognosis; Survival analysis; Surveillance, Epidemiology, and End Results Program

Core Tip: Log odds of negative lymph nodes/tumor size (LONS) was defined as the log of the ratio between negative lymph node count and the tumor size and has been first reported as a survival predictive tool in our study. Univariate and multivariate analyses confirmed LONS as an independent prognostic factor for stage I to III rectal cancer. The X-tile program demonstrated that the optimal cutoff was -0.8. Stratified analysis and Kaplan-Meier curves showed a significant improvement in the 10-year cancer-specific survival and overall survival in the high LONS group independent of clinicopathological factors.