According to a study reported in the May 8, 2007 Journal
of the American Medical Association, HCV infection also appears to increases
the risk of developing certain types of lymphoma (cancers of the lymphatic system
Leukaemias
and lymphomas are cancers which affect the cells which are part of the fluids
circulating around the body.
Researchers conducted a retrospective cohort study to test the hypothesis that HCV infection
may be associated with increased risk for hematological malignancies, related
lymphoproliferative disorders, and thyroid cancer.
They
analyzed data from patients who sought medical care at U.S. Veterans Affairs (VA)
facilities between 1997 and 2004. The cohort included 146,394 patients with HCV
who made at least 2 visits, as well as 572,293 patients without HCV. The mean
age of the patients was 52 years, 97% were men, most were white, and most had
served during the Vietnam era. HIV positive individuals were excluded.
To
assemble the HCV-uninfected control cohort, the researchers randomly selected
up to 4 HCV negative patients per HCV-infected patient from all veterans matched
for age, sex, and baseline visit date and type (inpatient or outpatient).
Results
·Over more
than 5 years of follow-up, 1359 patients were diagnosed with non-Hodgkin lymphoma
(NHL), 165 with Waldenström macroglobulinemia (a rare form of lymphoma), and 551
with cryoglobulinemia.
·The risk
of developing all 3 conditions was elevated in patients with HCV infection:
o28% greater
risk for NHL (adjusted hazard ratio 1.28);
onearly triple
the risk for Waldenström macroglobulinemia (adjusted HR 2.76)
oabout 4
times the risk for cryoglobulinemia (adjusted HR 3.98).
·No significant
increase in risk was observed for other hematological malignancies.
·Although
the risk of thyroiditis (thyroid inflammation) was slightly increased, the risk
for thyroid cancer (320 cases) was not elevated (adjusted HR 0.72).
Conclusions
“Hepatitis
C virus infection confers a 20% to 30% increased risk of non-Hodgkin lymphoma
overall, and a 3-fold higher risk of Waldenström macroglobulinemia, a low-grade
lymphoma,” the authors concluded. “Risks were also increased for cryoglobulinemia.
These results support an etiological role for HCV in causing lymphoproliferation
and causing non-Hodgkin lymphoma.”
However,
the overall risk of lymphoma remained low; based on these results, HCV infection
would increase the risk of developing lymphoma by just 1 case (from 5 to 6 cases)
per 500 patients over 10 years.
Lead
author Thomas Giordano, MD, from Baylor College of Medicine in Houston said that
effective hepatitis C treatment potentially could reduce the risk of developing
lymphoma.
It is unclear why HCV infection would increase the risk
of lymphoma, but the authors suggested that chronic stimulation of the immune
system may play a role. Epstein-Barr virus (EBV) is also associated with certain
types of lymphoma.
Although
this analysis did not include HIV positive patents, HIV-HCV coinfected individuals
would be expected to be at higher risk, since HIV-related immune deficiency is
also a risk factor for lymphoma, and NHL is considered an AIDS-defining condition.
Department
of Medicine, Baylor College of Medicine, Houston Center for Quality of Care and
Utilization Studies, Health Services Research and Development Service, Michael
E. DeBakey Veterans Affairs Medical Center, Houston, TX; National Cancer Institute,
National Institutes of Health, Rockville, MD.
05/18/07
References TP Giordano, L Henderson, O Landgren, and others. Risk of
Non-Hodgkin Lymphoma and Lymphoproliferative Precursor Diseases in US Veterans
With Hepatitis C Virus. JAMA 297(18): 2010-2017. May 9, 2007.
