Risk of hepatocellular carcinoma and cancers at other sites among patients diagnosed with chronic hepatitis B virus infection in Sweden.

Hepatitis B virus (HBV) infection is one of most common viral infections worldwide. While chronic HBV infection has been shown consistently to be associated with hepatocellular carcinoma, data on associations with cancers at other sites are limited. In this study a total of 10,197 patients were diagnosed with chronic HBV infection in Sweden, and they were retrieved from the nationwide Swedish Hospital Discharge Register and Outpatient Register and linked to Cancer Registry data. Standardized incidence ratios (SIRs) for cancers were calculated for these patients in comparison with the population without HBV infection. Five hundred sixty-seven of whom developed cancer (SIR 1.82 (95% confidence interval (CI) 1.67-1.97)) during the study period. The SIR for hepatocellular carcinoma in patients with HBV infection was 40.58 (95% CI 30.50-50.07). In addition, a total of seven other cancer sites/types showed increased SIRs: cancers of the upper aerodigestive tract, lung, kidney, skin (squamous cell carcinoma), and thyroid gland, and lymphoma and leukemia. The risks of non-Hodgkin lymphoma and acute myeloid leukemia were increased in both Swedish- and foreign-born patients with HBV infection. In summary, chronic HBV infection is a strong risk factor for hepatocellular carcinoma and also increases the risk of seven other cancers. These findings illustrate the need for surveillance for cancers other than hepatocellular carcinoma in patients with HBV infection.