Impact of hepatitis C virus treatment on the risk of non-hepatic cancers among hepatitis C virus-infected patients in the US

Background: Hepatitis C virus (HCV) infection is associated with with an increased risk of non-hepatic cancers, but the impact of HCV treatment on non-hepatic cancer is unclear. Aims: To assess if HCV treatment reduced the incidence of non-hepatic cancers among patients with chronic HCV infection in the US. Methods: We conducted a retrospective cohort study in MarketScan Databases from January 2005 to December 2016. Multivariable, time-varying Cox proportional-hazards models were used to determine hazard ratios (HRs) of incident non-hepatic cancers in treated and untreated patients with HCV infection. We conduscted subgroup analyses for sex, age, and presence of cirrhosis or diabetes. Results: Among 62 078 patients with newly diagnosed HCV infection, 17 302 (28%) initiated HCV treatment, among whom 15 322 completed 8-16 weeks treatment (minimally effective treatment). Patients who initiated HCV treatment had an 11% decreased risk of developing an incident non-hepatic cancer compared to untreated patients (HR = 0.89, 95% confidence interval (Cl) = 0.82-0.96). The reduction was slightly higher when patients completed a minimally effective treatment (HR = 0.87; 95% Cl = 0.80 - 0.95). This was observed in most subgroup analyses for those who had a minimally effective treatment including patients with cirrhosis. When we stratified cancer or therapy subtypes, the association remained consistent for pancreatic and lung cancers, and dual HCV therapy. Conclusions: HCV treatment led to a significantly reduced incidence of non-hepatic cancers among patients with HCV infection. Despite discrepancies between cancer or HCV therapy subtypes, our findings suggest that treating HCV infection can decrease the extrahepatic cancer burden associated with chronic HCV infection.