Meta-Analysis
Copyright ©The Author(s) 2020. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Oncol. Dec 15, 2020; 12(12): 1443-1455
Published online Dec 15, 2020. doi: 10.4251/wjgo.v12.i12.1443
Prognostic impact of at least 12 lymph nodes after neoadjuvant therapy in rectal cancer: A meta-analysis
Ling Tan, Zi-Lin Liu, Zhou Ma, Zhou He, Lin-Han Tang, Yi-Lei Liu, Jiang-Wei Xiao
Ling Tan, Zi-Lin Liu, Zhou Ma, Zhou He, Lin-Han Tang, Yi-Lei Liu, Jiang-Wei Xiao, Department of Gastrointestinal Surgery, Clinical Medical College and The First Affiliated Hospital of Chengdu Medical College, Chengdu 610500, Sichuan Province, China
Author contributions: Tan L and Liu ZL performed data acquisition, analysis, and interpretation, and drafted the manuscript; Ma Z, He Z, Tang LH, and Liu YL contributed to data interpretation and revised the manuscript; Xiao JW contributed to study conception and design, and critical revision of the manuscript; all authors approved the final version of the submitted manuscript.
Supported by the National Natural Science Foundation of China, No. 81070378 and 81270561; and Special Research Fund for The First Affiliated Hospital of Chengdu Medical College, No. CYFY2019YB08.
Conflict-of-interest statement: All the authors declare that they have no conflict of interest to disclose.
PRISMA 2009 Checklist statement: The authors have read the PRISMA 2009 Checklist, and the manuscript was prepared and revised according to the PRISMA 2009 Checklist.
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: Jiang-Wei Xiao, MD, PhD, Postdoc, Professor, Surgeon, Surgical Oncologist, Teacher, Department of Gastrointestinal Surgery, Clinical Medical College and The First Affiliated Hospital of Chengdu Medical College, No. 278 Zhongduan Baoguang Avenue, Xindu District, Chengdu 610500, Sichuan Province, China. xiaojiangwei2018@163.com
Received: August 5, 2020
Peer-review started: August 5, 2020
First decision: September 24, 2020
Revised: September 28, 2020
Accepted: October 20, 2020
Article in press: October 20, 2020
Published online: December 15, 2020
Processing time: 127 Days and 4.2 Hours
ARTICLE HIGHLIGHTS
Research background

Neoadjuvant therapy significantly reduces the number of yielded lymph nodes (LNs) for rectal cancer, and the number of dissected LNs in rectal cancer after neoadjuvant therapy has a controversial effect on the prognosis.

Research motivation

Studies have shown that the number of LNs after rectal cancer is significantly reduced after neoadjuvant therapy. Some scholars have found that less than 12 LNs in rectal cancer patients receiving neoadjuvant radiotherapy should be considered as a better prognostic factor. However, others believe that dissecting at least 12 LNs is an independent and favorable prognostic factors for rectal cancer after neoadjuvant therapy. Therefore, it is necessary to conduct a meta-analysis to systematically and comprehensively study the influence of the number of LNs retrieved after neoadjuvant treatment on the survival outcome of patients with rectal cancer.

Research objectives

To evaluate the effect of LN production in rectal cancer after neoadjuvant treatment on survival through meta-analysis.

Research methods

The meta-analysis methods were adopted to realize the objectives.

Research results

Nine articles were included in the meta-analyses. Statistical analysis revealed a statistically significant difference in overall survival (OS) [hazard ratio (HR) = 0.76, 95% confidence interval (CI) = 0.66-0.88, I2 = 12.2%, P = 0.336], disease-free survival (DFS) (HR = 0.76, 95%CI: 0.63-0.92, I2 = 68.4%, P = 0.013), and distant recurrence (DR) (HR = 0.63, 95%CI: 0.48-0.93, I2 = 30.5%, P = 0.237) between the LNs ≥ 12 and LNs < 12 groups, but local recurrence (HR = 0.67, 95%CI: 0.38-1.16, I2 = 0%, P = 0.348) showed no statistical difference. Moreover, subgroup analysis of LN negative patients revealed a statistically significant difference in DFS (HR = 0.67, 0.95%CI: 0.52-0.88, I2 = 0%, P = 0.565) between the LNs ≥ 12 and LNs < 12 groups.

Research conclusions

This meta-analysis confirmed that dissecting at least 12 LNs after neoadjuvant therapy may improve the patients’ OS, DFS, and DR.

Research perspectives

Some limitations in this analysis should be handled carefully. The most important limitation is that the included studies are all retrospective. Because some potential deviations are difficult to adjust, further careful design and large-scale randomized controlled trial experiments are needed to determine the effect of the number of anatomical LNs on the prognosis of rectal cancer after neoadjuvant treatment. In addition, because neoadjuvant therapy reduces LN yield, further research is needed on the impact of different LN numbers on prognosis, such as 6 LNs, 7 LNs, and 8 LNs.