Hepatitis B was already known to cause liver cancer and some scientists had suspected it might cause lymphoma, too. The study, published in Lancet Oncology, confirms this. Hepatitis C is also linked to lymphoma.
The blood cancer is not common and widespread vaccination against the viruses is unlikely to affect non-Hodgkin lymphoma rates much, the researchers noted. But it may be possible to treat the virus and help non-Hodgkin lymphoma patients, they said.
Dr. Eric Engels of the U.S. National Cancer Institute and Sun Ha Jee of Yonsei University in Seoul studied the records of more than 600,000 people in South Korea, where hepatitis B was extremely common before a vaccination campaign began in 1995.
Of these, 53,000 or about 9 percent had evidence of hepatitis B infection. After 14 years, rates of non-Hodgkin lymphoma were more common among the infected people — 19.4 cases per 100,000 people compared to 12.3 per 100,000 who did not have hepatitis B.
Viral hepatitis is the leading cause of liver cancer and the most common reason for liver transplantation, according to the U.S. Centers for Disease Control and Prevention. The various hepatitis viruses are not closely related — the word hepatitis means inflammation of the liver.
An estimated 350 million people worldwide are infected with hepatitis B virus, which causes 340,000 cases of liver cancer a year and kills between 500,000 and 1.2 million people a year.
Researchers think both hepatitis B and C may cause lymphoma by overstimulating the immune system as it tries to fight off the liver infection.