Hepatitis C virus infection causes liver cancer and cirrhosis.
It may also increase the risk of other tumors, particularly hematopoietic malignancies and thyroid cancer.
Previous studies have been too small to adequately assess these risks.
|Hep C confers up to 30% increased risk of non-Hodgkin lymphoma|
|The Journal of the American Medical Association|
Dr Thomas Giordano and colleagues from Texas evaluated whether Hepatitis C virus infection is associated with increased risk for hematological malignancies.
The investigative team also assessed whether Hepatitis C virus infection increases the risk of related lymphoproliferative disorders, and thyroid cancer.
The team conducted a retrospective cohort study of users of US Veterans Affairs health care facilities from 1997 to 2004.
The investigators identified 146,394 patients infected with Hepatitis C virus who had at least 2 visits with a diagnostic code for Hepatitis C virus infection.
The team compared these to 572,293 patients uninfected with Hepatitis C virus.
To assemble the Hepatitis C virus-uninfected cohort, the team randomly selected up to 4 patients per patient infected with Hepatitis C virus.
The veterans were matched on age, sex, and baseline visit date and type.
Individuals with human immunodeficiency virus were excluded.
The team evaluated risks of hematopoietic malignancies, related lymphoproliferative precursor diseases, and thyroid cancer.
The investigators adjusted for selection factors, race, era of military service, and use of medical services.
The mean age of the patients was 52 years, and 97% were men.
The team found that the risks for non-Hodgkin lymphoma, Waldenström macroglobulinemia, and cryoglobulinemia were increased with Hepatitis C virus.
The team found no significantly increased risk for other hematological malignancies.
Although thyroiditis risk was slightly increased, the team observed the risk for thyroid cancer was not.
The team noted that Hepatitis C virus infection confered a 20% to 30% increased risk of non-Hodgkin lymphoma overall.
Hepatitis C virus infection also had a 3-fold higher risk of Waldenström macroglobulinemia, a low-grade lymphoma.
The researchers observed that risks were also increased for cryoglobulinemia.
Dr Giordano's team concluded, "These results support an etiological role for Hepatitis C virus in causing lymphoproliferation and causing non-Hodgkin lymphoma."