Chronic Hepatitis C Virus Infection is Associated with an Increased Risk of Lung Cancer: A Systematic Review and Meta-analysis.

Background: Chronic hepatitis C virus (HCV) infection is associated with increased risk of hepatocellular carcinoma. However, whether HCV infection also increases the risk of extra-hepatic cancer is still not well-established. This systematic review and meta-analysis was conducted in order to investigate the relationship between chronic HCV infection and lung cancer.
Materials and Methods: A systematic review was performed using MEDLINE and EMBASE databases from inception to November 2019 with search strategy that included the terms for "hepatitis C virus" and "cancer". Eligible studies must be cohort studies that included patients with chronic HCV infection and comparators without HCV infection, then followed them for incident lung cancer. Relative risk, incidence rate ratio, standardized incidence ratio or hazard risk ratio of this association along with associated 95% confidence interval (CI) were extracted from each eligible study and combined for the calculation of the pooled effect estimate using the random effect, generic inverse variance method.
Results: A total of 20,459 articles were identified using the aforementioned search strategy. After two rounds of review, eight studies fulfilled the inclusion criteria and were included into the meta-analysis. Chronic HCV infection was significantly associated with an increased risk of lung cancer with the pooled relative risk of 1.94 (95% CI 1.56-2.42; I ²  = 87%). Funnel plot was fairly symmetric and not suggestive of presence of publication bias.
Conclusions: The current study demonstrated that chronic HCV infection is significantly associated with a 1.94-fold increased risk of developing lung cancer. However, further studies are still needed to investigate if this association is causative.