Researchers from the United States and South Korea have found that patients suffering from Hepatitis B infection stand twice the risk of developing a deadly form of blood cancer called non-Hodgkin lymphoma.

Hepatitis B is a liver infection caused by a virus. The infection results in sustained immune system activation that may cause the immunity-triggering white blood cells to develop DNA mutations and leading up to non-Hodgkin lymphoma (NHL), researchers say.

The researchers analyzed data of 603,585 participants tested positive for hepatitis B virus (HBV) at baseline from the Korean Cancer Prevention Study and found that 53,045 or nine percent of the participants tested positive for HBV at baseline.

When they followed up the participants for the next 14 years, 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, says the study published in the medical journal Lancet Oncology.

The study further noted 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 report says.

The study included people in South Korea, where hepatitis B 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.

This is the first large study to prove the association between hepatitis b infection non-Hodgin's lymphoma. Even though hepatitis C infection has been linked with increased risk of non-Hodgkin lymphoma in earlier studies, no large studies have been conducted so far to establish the connection between hepatitis B and lymphoma.