No Link Found Between Contaminated
CHICAGO, IL -- January 27, 1998 -- Americans who were administered a polio vaccine that was contaminated with an ape virus are not at increased risk for cancer, according to an article in tomorrow's issue of The Journal of the American Medical Association. (1)
Howard Strickler, M.D., M.P.H., from the National Cancer Institute, Bethesda, MD., and colleagues determined the risk of developing rare human tumours among Americans who received the contaminated vaccine. The DNA of simian virus 40 (SV40) has recently been detected in tumours including ependymoma (brain tumour), osteosarcoma (bone tumour), and mesothelioma (tumour of the lining of the lung and chest cavity).
The vaccine was given to tens of millions of Americans between 1955 and 1963. By 1961, between 80 and 90 percent of all U.S. children younger than 20 years had been injected with the vaccine containing SV40. The virus can cause cancer in rodents.
"Our study failed to detect any significant increases in the risk of cancers reported to contain SV40 DNA among the birth cohorts exposed to SV40-contaminated vaccine," the authors write. "In effect, ependymomas and osteosarcomas have remained rare cancers, while the rising rates for mesotheliomas have involved older age groups unlikely to have received SV40-contaminated vaccine.
"Thus, approximately 30 years after millions of Americans were parenterally exposed as infants or children, the absence of a discernable effect in our study adds to the evidence that no relation exists between exposure to SV40-contaminated vaccine and the development of cancer. As the exposed cohorts mature, however, it will be important to continue monitoring of cancer risks.
"It is important that this report not be viewed as strong evidence against the role of SV40 as a human pathogen. For example, SV40 may have been in the human population for some time, unrelated to vaccine exposure, as suggested by the finding of SV40 antibodies in serum samples around the world that were collected before introduction of poliovirus vaccines. It is also possible that SV40 only has tumourigenic [causing tumours] potential in humans exposed under different conditions and higher levels of virus than were associated with poliovirus vaccine."
1. HD Strickler. Contamination of poliovirus vaccines with simian virus 40 (1995-1963) and subsequent cancer rates. JAMA; 279:4; 292-5