Hepatitis C viral infection increases the risk of lymphoid‐neoplasms: A population‐based cohort study

Chronic hepatitis C viral (HCV) infection has been associated with non-Hodgkin's lymphoma (NHL); however, the results are inconsistent among regions with different HCV prevalence rates. The temporal relationship, risk estimates, and association between HCV and lymphoid-neoplasms remain unclear. This study investigated the temporal relationship between HCV infection and lymphoid-neoplasms using a nationwide population-based cohort. Patients with chronic HCV infection were retrieved from the Taiwan National Health Insurance Research Database during 2001-2005 and designated as the HCV cohort. Those with prior malignancies or coinfected with hepatitis B or human immunodeficiency virus were excluded. The age, sex, and comorbidities, including rheumatological disorders and diabetes, were matched by propensity scores to another non-HCV cohort. Both cohorts were followed longitudinally until 2009 for a new diagnosis of any lymphoid-neoplasms or NHL. A total of 11,679 HCV and 46,716 non-HCV patients were included and followed for 8 years. The incidence rates of any lymphoid-neoplasms and NHL were significantly greater in the HCV cohort than the non-HCV cohort (48.4 versus 22.1, and 37.0 versus 17.5 per 100,000 person-years, respectively, both P < 0.001), even after we excluded lymphoid-neoplasms developed within the first year of follow-up. Cox proportional hazards regression analysis (after adjustment for age, sex, numbers of annual medical visits during follow-up, and comorbidities) indicated that HCV infection was associated with an increased risk of either any lymphoid-neoplasms (hazard ratio = 2.30, 95% confidence interval 1.55-3.43, P < 0.0001) or NHL (hazard ratio = 2.00, 95% confidence interval 1.27-3.16, P = 0.003). Conclusion: After adjustment for confounders and biases, chronic HCV infection is temporally associated with a two-fold increased risk of lymphoid-neoplasms, especially NHL, in Asian patients; additional large studies are needed to explore whether HCV eradication can reduce the incidence of lymphoid-neoplasms. (Hepatology 2016;63:721–730)