Biology Reference
In-Depth Information
Have Vaccines Been Linked to Cancer?
An increasing incidence of a type of tumor called fibrosarcoma has been
noted in locations on the body where vaccines are routinely adminis-
tered to cats. Research is being conducted and a national veterinary task
force exists to determine the relationship between vaccines and
fibrosarcomas. The incidence of vaccine site fibrosarcomas is estimated
at one to three out of every 10,000 vaccines administered, which is an
extremely low number.
The general consensus in the veterinary community is that the risk
of disease from not vaccinating is much higher than the risks associat-
ed with vaccinating, but a rethinking of how, when, where and why we
vaccinate cats has resulted. This is an extremely controversial issue for
veterinarians, and not all veterinarians are in agreement over which
vaccine protocols should be followed.
The information obtained so far from past and current research has
failed to pinpoint a specific cause of fibrosarcomas in cats. Initially it was
thought that aluminum adjuvants (chemicals added to a vaccine to
enhance its effectiveness), were responsible for tumors, and many cases
seemed to be linked to adjuvanted FeLV and rabies vaccines. Further
study showed that this is not necessarily true and that many types of
vaccines and other injectable products resulted in tumors in some cats.
Even vaccines that use newer recombinant DNA technology, touted as
unlikely to produce tumors, have been linked to tumors.
At this time the consensus is that the genetics of the individual cat
may be the most important factor in whether a cat develops vaccine-
associated sarcoma. Certain cats may carry genes that predispose them
to form tumors at sites of inflammation.Vaccines and other drugs cre-
ate various levels of inflammation where they are injected. Research is
ongoing, and should eventually find the answer.
