Interval between hepatocellular carcinoma treatment and interferon-free direct-acting antiviral agents against hepatitis C is necessary to suppress tumor recurrence.

Interferon (IFN) has been identified to suppress carcinogenesis when used for treating hepatitis C virus (HCV) infections. Treatment with IFN-free direct-acting antiviral agents (DAAs) is an acceptable alternative, even in elderly patients or patients who have been treated for hepatocellular carcinoma (HCC), because it has a lower incidence of side effects and higher sustained virological response (SVR) rate compared with IFN treatment. However, the suppression of carcinogenesis by DAAs is unclear. In the present study, 19 patients who underwent DAA treatment following treatment for HCC between January 2015 and March 2017 were retrospectively investigated. The clinical data were compared between 9 patients with HCC recurrence following DAA treatment (recurrence group) and 10 patients without HCC recurrence (no-recurrence group). The 1-year cumulative recurrence rate of HCC following SVR was as high as 50.2%. Age and sex did not significantly differ between the two groups, and the average number of HCC treatments prior to DAA treatment was also not significantly different between the recurrence and no-recurrence groups (3.2 and 2.2, respectively). The median interval between the final HCC treatment and the commencement of DAA treatment was 88 days in the recurrence group, which was significantly less compared with 790 days in the no-recurrence group (P=0.018). An interval of 120 days or more from final HCC treatment to the commencement of DAA treatment was a significant independent factor of no HCC recurrence following DAA treatment (P=0.028). A high HCC recurrence rate was identified following DAA treatment in patients with a history of HCC treatment. Therefore, there should be at least a 4-month interval from the final HCC treatment to the commencement of DAA treatment to ensure no HCC recurrence.