TUESDAY, Aug. 3 (HealthDay News) -- People with hepatitis B infection have about twice the risk of developing non-Hodgkin lymphoma, finds a new study.

Previous research has established that hepatitis C infection is linked with increased risk of non-Hodgkin lymphoma (NHL), but only small studies have been conducted on hepatitis B and NHL.

It's believed that liver infection caused by hepatitis results in sustained immune system activation that may trigger lymphocytes (white blood cells that are part of the immune system) to develop DNA mutations that can lead to NHL.

This study, published online Aug. 4 in The Lancet Oncology, included people in South Korea, where hepatitis B (HBV) was endemic until 1995 when the country began vaccination of all newborns. However, HBV infection remains common in adults because of infections acquired in childhood.

The researchers analyzed data from the Korean Cancer Prevention Study and found that 53,045 -- or 9 percent -- of 603,585 participants tested positive for HBV at baseline. During 14 years of follow-up, NHL was diagnosed in 133 people with HBV infection and 905 people who were HBV-negative.

The incidence of NHL was 19.4 per 100,000 person-years among those with HBV infection and 12.3 in those who were HBV-negative.

The American and South Korean researchers also found that people with HBV infection were nearly four times more likely to develop a rare condition called malignant immunoproliferation, a collection of immune disorders related to NHL.

"In this large cohort study of health workers and their families in South Korea, we documented an excess risk of NHL in people infected with HBV ... Additional research is needed to clarify whether the association between HBV infection and NHL is causal," the researchers wrote in a news release from the journal publisher.

"For HCV-infected patients with low-grade NHL [especially marginal zone lymphomas], HCV treatment seems effective for hematological remission. Thus, we speculate that treatment directed at HBV in similar low-grade NHLs might lead to a clinical response and remove the need for chemotherapy. Further investigation in appropriate clinical series will be important," they concluded.

More information

The U.S. Centers for Disease Control and Prevention has more about hepatitis B.