Background:
Hepatitis C virus (HCV) infection causes hepatocellular carcinoma (HCC) and subtypes of non-Hodgkin lymphoma (NHL). Associations with other cancers are not established. We systematically assessed associations between HCV infection and cancers in the US elderly population.
Methods:
We conducted a registry-based case-control study using the SEER-Medicare data in US adults aged ≥66 years. Cases (n=1,623,538) were people with first cancers identified in SEER registries (1993–2011). Controls (n=200,000) were randomly selected cancer-free individuals frequency-matched to cases on age, sex, race, and calendar year. We determined associations with HCV using logistic regression.
Results:
HCV prevalence was higher in cases than controls (0.7% vs. 0.5%). HCV was positively associated with cancers of the liver (adjusted odds ratio [aOR]=31.5; 95%CI=29.0–34.3), intrahepatic bile duct (aOR=3.40; 95%CI=2.52–4.58), extrahepatic bile duct (aOR=1.90; 95%CI=1.41–2.57), pancreas (aOR=1.23; 95%CI=1.09–1.40), anus (aOR=1.97; 95%CI=1.42–2.73), and non-melanoma non-epithelial skin cancer (aOR=1.53; 95%CI=1.15–2.04), myelodysplastic syndrome (aOR=1.56; 95%CI=1.33–1.83), and diffuse large B-cell lymphoma (DLBCL) (aOR=1.57; 95%CI=1.34–1.84). Specific skin cancers associated with HCV were Merkel cell carcinoma (aOR=1.92; 95%CI=1.30–2.85) and appendageal skin cancers (aOR, 2.02; 95%CI=1.29–3.16). Inverse associations were observed with uterine cancer (aOR=0.64; 95%CI=0.51–0.80) and prostate cancer (aOR=0.73; 95%CI=0.66–0.82). Associations were maintained in sensitivity analyses conducted among people without documented alcohol abuse, cirrhosis, or hepatitis B or human immunodeficiency virus infections, and after adjustment for socioeconomic status. Associations of HCV with other cancers were not observed.
Conclusion(s):
HCV is associated with increased risk of cancers other than HCC in the US elderly population, notably bile duct cancers and DLBCL. These results support a possible etiologic role for HCV in an expanded group of cancers.