Published online Aug 6, 2021. doi: 10.12998/wjcc.v9.i22.6357
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
Processing time: 161 Days and 12 Hours
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.
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.
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.
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].
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%).
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.
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.