News Release

Contaminated poliovirus vaccine not associated with cancer

Peer-Reviewed Publication

Journal of the National Cancer Institute

Exposure to poliovirus vaccine that was contaminated with simian virus 40 (SV40) does not appear to be associated with increased cancer incidence in Denmark, according to a large population-based study appearing in the April 2 issue of the Journal of the National Cancer Institute.

Poliovirus vaccines that were inadvertently contaminated with SV40 were given to tens of millions of people worldwide before SV40 was discovered in 1960. Since then, SV40 has been linked to a variety of cancers in rodents, and SV40 DNA has been identified in human tumors, including mesothelioma, brain tumors, bone tumors, non-Hodgkin's lymphoma, leukemia, and testicular carcinoma.

In Denmark, SV40-contaminated poliovirus vaccine was widely used between 1955 and 1962. Eric A. Engels, M.D., of the National Cancer Institute, and his colleagues used cancer incidence data from 1943 through 1997 from the Danish Cancer Registry to examine the incidence of cancer among three Danish birth cohorts who had either been exposed to the SV40-contaminated vaccine or who had not been exposed to the vaccine as children or infants. They also examined cancer incidence among children who were 0 to 4 years old before, during, and after the period of vaccine contamination, to determine whether the risk of childhood cancers was elevated following exposure to SV40-contaminated poliovirus vaccine.

The authors found that the risk of cancer among individuals exposed to SV40-contaminated poliovirus vaccine was no higher than the risk of cancer among individuals not exposed to the contaminated vaccine. Moreover, there was no increase in cancer incidence among children aged 0 to 4 years who were exposed to SV40-contaminated poliovirus vaccine.

"Our population-based, retrospective follow-up does not appear to support the hypothesis that SV40 is a cause of human cancer," the authors write. However, because of conflicting laboratory and epidemiologic findings, more research is needed to settle the issue, they say. "Whether SV40 is transmitted among humans is a relevant question, and this question could be addressed by future epidemiologic studies that use serologic (blood-based) tests currently under development," the authors write. "Given the widespread exposure of SV40-contaminated vaccines in the 1950s and early 1960s, this issue remains of public health importance."

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Contact: NCI Office of Communications, 301-496-6641; fax: 301-496-0846, ncipressofficers@mail.nih.gov

Engels EA, Katki HA, Nielsen NM, Winther JF, Hjalgrim H, Gjerris F, et al. Cancer incidence in Denmark following exposure to poliovirus vaccine contaminated with simian virus 40. J Natl Cancer Inst 2003;95:532–9.

Note: The Journal of the National Cancer Institute is published by Oxford University Press and is not affiliated with the National Cancer Institute. Attribution to the Journal of the National Cancer Institute is requested in all news coverage.


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