Hepatitis C virus infection and risk of thyroid cancer: A systematic review and meta-analysis.

Purpose: Several epidemiological studies investigated the relationship between hepatitis C virus (HCV) infection and risk of thyroid cancer, but the results were not consistent. A systematic review and meta-analysis was conducted to assess the impact of HCV infection on thyroid cancer risk.

Methods: The literature was searched up to March 15, 2016 for case-control or cohort studies on the association between HCV infection and thyroid cancer risk. The summary relative risks (RR) and 95% confidence intervals (CI) were calculated.

Results: Five studies (two case-control studies and three cohort studies) were included in the meta-analysis, with a total of 751,551 participants and 367 cases of thyroid cancer. Meta-analysis of those 5 studies found that there was no statistically significant association between HCV infection and thyroid cancer risk (summary RR=2.09, 95%CI 0.78-5.64, p=0.145; I=81.2%). However, HCV infection was significantly associated with increased risk of thyroid cancer (summary RR=2.86, 95%CI 1.63-5.03, p=0.003; I=24.9%) after adjusting the heterogeneity.

Conclusion: There is a possible association between HCV infection and increased risk of thyroid cancer, and more cohort studies are needed to validate the possible association.