Contaminated poliovirus vaccine not associated with cancer
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."
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;95:5329.
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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