Association between chronic hepatitis C virus infection and esophageal cancer: A systematic review and meta-analysis

Background: Chronic hepatitis C virus (HCV) infection is associated with increased risk of hepatobiliary tract cancer. However, whether chronic HCV infection is also associated with elevated risk of other types of cancer is still unknown. This systematic review and meta-analysis was conducted in order to investigate whether chronic HCV infection is positively associated with esophageal cancer. Methods: A systematic review was conducted using Embase and MEDLINE databases from inception to November 2019, with a search strategy that comprised the terms for "hepatitis C virus"and "cancer."Eligible studies were cohort studies consisting of patients with chronic HCV infection and comparators without HCV infection, and followed them for incident esophageal cancer. Hazard risk ratio, incidence rate ratio, relative risk or standardized incidence ratio of this association were extracted from each eligible study along with their 95% confidence intervals and were combined to calculate the pooled effect estimate using the random effect, generic inverse variance method. Results: A total of 20,459 articles were identified using this search strategy. After 2 rounds of independent review, 7 studies satisfied the inclusion criteria and were included in the meta-analysis. Chronic HCV infection was significantly associated with a higher incidence of esophageal cancer with the pooled relative risk of 1.61 (95% confidence interval: 1.19-2.17; I 2=39%). The funnel plot was relatively symmetric which was not suggestive of publication bias. Conclusion: This systematic review and meta-analysis demonstrated that there is a modest association between chronic HCV and incident esophageal cancer. However, more studies are needed to investigate the causality of this association.