Meta-Analysis
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Aug 6, 2021; 9(22): 6357-6379
Published online Aug 6, 2021. doi: 10.12998/wjcc.v9.i22.6357
Neoadjuvant chemotherapy for patients with resectable colorectal cancer liver metastases: A systematic review and meta-analysis
Yue Zhang, Long Ge, Jun Weng, Wen-Yu Tuo, Bin Liu, Shi-Xun Ma, Ke-Hu Yang, Hui Cai
Yue Zhang, Jun Weng, Wen-Yu Tuo, Bin Liu, Shi-Xun Ma, Hui Cai, General Surgery Clinical Medical Center, Gansu Provincial Hospital, Lanzhou 730000, Gansu Province, China
Long Ge, Ke-Hu Yang, Evidence Based Social Science Research Center, School of Public Health, Lanzhou University, Lanzhou 730000, Gansu Province, China
Author contributions: Zhang Y, Ge L, Yang KH, and Cai H designed research; Zhang Y, Weng J, Tuo WY, Ma SX, and Liu B conducted the literature search; Zhang Y and Ge L collected and retrieved the data; Zhang Y, Weng J, and Tuo WY analyzed the data; Zhang Y wrote and revised the manuscript; All authors approved the final version.
Supported by the Natural Science Foundation of Gansu Province, China, No. 18JR3RA052; the Gansu Province Da Vinci Robot High End Diagnosis and Treatment Personnel Training Project; the National Key Research and Development Program Task Book, No. 2018YFC1311506; and the Lanzhou Talent Innovation and Entrepreneurship Project Task Contract, No. 2016-RC-56.
Conflict-of-interest statement: No conflict of interest.
Data sharing statement: No additional data are available.
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: Hui Cai, MD, PhD, Chief Doctor, Director, Professor, Surgical Oncologist, General Surgery Clinical Medical Center, Gansu Provincial Hospital, No. 204 Donggang West Road, Lanzhou 730000, Gansu Province, China. Caialonteam@163.com
Received: February 16, 2021
Peer-review started: February 16, 2021
First decision: April 6, 2021
Revised: April 14, 2021
Accepted: June 16, 2021
Article in press: June 16, 2021
Published online: August 6, 2021
ARTICLE HIGHLIGHTS
Research background

Surgery is an effective method for the treatment of liver metastases from colorectal cancer, but the risk of recurrence and metastasis is higher after surgery. The use of neoadjuvant chemotherapy (NAC) for the treatment of resectable colorectal cancer liver metastases is still controversial.

Research motivation

Many previous studies have reported the efficacy of adding NAC in the surgical treatment of resectable liver metastases from colorectal cancer. However, their conclusions have been inconsistent. A randomized controlled trial has revealed that NAC can confer a significant survival advantage over disease-free survival (DFS). In order to solve this dispute systematically and comprehensively, it is necessary to conduct a meta-analysis.

Research objective

The purpose of this study is to use a systematic review and meta-analysis to evaluate the application value of NAC in patients with resectable colorectal cancer and liver metastases.

Research method

We searched PubMed, Embase, Web of Science, and the Cochrane Library to collect clinical studies comparing NAC with non-NAC. Data processing and statistical analyses were performed using Stata V.15.0 and Review Manager 5.0 software. The odds ratio (OR) and 95% confidence interval (CI) were employed to analyze the dichotomous variables. Meanwhile, the standardized mean difference (SMD) with a 95%CI was used to analyze the continuous variables. In addition, the hazard ratio (HR) was used as a summary statistical measure of survival outcome [5-year overall survival (OS) and 5-year DFS].

Research results

Thirty-two studies involving 11236 patients were included in this analysis, which included 31 retrospective cohort studies and one randomized controlled trial. Our results showed a statistically significant difference in the 5-year OS (HR = 0.49, 95%CI: 0.39-0.61 P = 0.000), 5-year DFS (HR = 0.48 95%CI: 0.36-0.63 P = 0.000), the duration of surgery (SMD = 0.41, 95%CI: 0.01-0.82, P = 0.044), the number of liver metastases (SMD = 0.73, 95%CI: 0.02-1.43, P = 0.043), and the number of lymph node metastasis (SMD = 1.24, 95%CI: 1.07-1.43, P = 0.004). However, our results showed no statistically significant difference in the combined effect size in terms of the incidence of surgical site infection (OR = 0.94, 95%CI: 0.76-1.16, P = 0.571, I² = 27.7%), bile leakage (OR = 1.10, 95%CI: 0.84-1.43, P = 0.481, I² = 0.00%), and liver failure (OR = 1.04, 95%CI: 0.76-1.42, P = 0.329, I² = 13.4%).

Research conclusions

NAC can significantly improve the long-term survival advantages of colorectal liver metastases patients, including 5-year OS and 5-year DFS. At the same time, it does not increase the incidence of postoperative bile leakage, surgical site infection, liver failure, and other complications.

Research perspectives

This study had several limitations: First, the included original research studies were mostly from Europe and America, which may affect the accuracy and credibility when comparing studies from different regions. Second, the representative sample size was relatively low. Furthermore, most of the studies that we included were observational studies, which may adversely affect the quality of the study results. Moreover, this study was a secondary study, and it was impossible to control the differences among the original studies, which may have affected the reliability of the results. Finally, colorectal liver metastases is a heterogeneous disease, and differences in tumor biology and expressed proteins may cause significant bias.