|Risk of Lymphoma Increases with Hepatitis C
People infected with the hepatitis C virus (HCV) are at an increased
risk of developing certain lymphomas (cancers of the lymphatic
system), according to a study published in the May 8, 2007, issue
of the Journal of the American Medical Association. Researchers
from the National Cancer Institute (NCI), part of the National
Institutes of Health, and Baylor College of Medicine, found that
HCV infection increased the risk of developing non-Hodgkin’s lymphoma
by 20 percent to 30 percent. The risk of developing Waldenström’s
macroglobulinemia (a rare type of non-Hodgkin’s lymphoma) went
up by 300 percent and the risk for cryoglobulinemia, a condition
marked by abnormal levels of certain antibodies in the blood, was
also elevated for those with HCV infections.
The researchers looked at patient records collected from Veterans
Affairs (VA) hospitals across the United States between 1996 and
2004. Researchers selected more than 700,000 records; 146,394 represented
patients who were diagnosed with the hepatitis C virus, while 572,293
represented patients who were not. Based on that review, researchers
determined, first, that the patients infected with HCV had a higher
risk of developing lymphoma and, second, that HCV infection preceded
development of the lymphoma. The risk of lymphomas in HCV-infected
patients was charted across more than five years of follow-up.
“This is one of the largest studies ever conducted to look at
the relationship between hepatitis C virus infection and cancers
of the lymphatic system,” said NCI Director John E. Niederhuber,
M.D. “Since so much is still unknown about the causes of lymphoma,
establishing which factors contribute to the disease is the first
step in finding ways to reduce its incidence and lessen mortality.”
HCV causes hepatitis, which is an inflammation of the liver. The
HCV virus is carried through the blood and is passed from person
to person through the exchange of bodily fluids — via shared
needles, open wounds, and sexual contact, and other means. HCV
is also known to cause cirrhosis and liver cancer.
“Although the risk of developing lymphomas is small, our research
suggests that screening of HCV-infected individuals could identify
conditions which may lead to cancer. It might then be possible
to prevent progression to lymphoma,” said investigator Eric A.
Engels, M.D., from the Viral Epidemiology Branch of NCI’s Division
of Cancer Epidemiology and Genetics. “More research is needed to
further clarify the relationship between HCV infection and lymphoma.”
In the United States, there are more than 4.1 million people living
with hepatitis C virus infection — about 1.6 percent of the
population. In 2007, it is estimated that 71,380 Americans will
be diagnosed with some type of lymphoma, which will take 19,730
The researchers note that this study was limited to military veterans
who used the VA system, so the results may not be applicable to
the overall U.S. population. The study population was mostly men
(97 percent), the majority of patients were white, and the average
age was 52 years. Patients in the HCV-infected group were more
likely to have served during the Vietnam era (1964-1975) than were
uninfected patients in the comparison group.
Previous studies found that the prevalence of HCV infection is
much higher among U.S. veterans who use the VA medical system (5
percent) than in the general population, where only 1.6 percent
carry the virus. Several factors have likely contributed to this
higher prevalence, including demographics, socioeconomic status,
and particularly a history of injection drug use or blood transfusions
received before 1990, when screening for hepatitis C virus was
This study was funded in part by the Intramural Research Program
of the National Cancer Institute, part of the National Institutes
of Health, and the Michael E. DeBakey Veterans Affairs Medical
Center in Houston, Texas.
For more information about cancer, visit http://www.cancer.gov,
or call NCI's Cancer Information Service at 1-800-4 CANCER.
For more information on Dr. Engels’ research, go to http://dceg.cancer.gov/people/EngelsEric.html.
For more information on NCI’s Viral Epidemiology Branch, go to http://dceg.cancer.gov/viral.html.
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