This has been established as a known factor, specifically for rabies and feline leukemia vaccines, says the University of Florida's Small Animal Hospital.
Dr. Julie Levy of the University's College of Veterinary Medicine commented that “one to ten cats out of every 10,000 vaccinated against infectious diseases develop cancer at the vaccine injection site.”
Historically, the injection site was located between the shoulder blades, which made treatment - excision of the tumor with clean margins - virtually impossible.
So in 2006, the Winn Feline Foundation recommended that the injection site be moved to a location where a tumor might more easily be removed.
The location recommended was either a front or back leg. The AAFP (American Association of Feline Practitioners) went even farther, suggesting the injections be made below the elbow or knee joint.
Studies of cats whose injection sites had moved to an intramuscular location such as the leg then began to show an increase in fibrosarcomas at that location. This uptick put to rest any doubts that vaccines (and possibly the adjuvants added to the vaccine to increase its effectiveness) were indeed to blame.
So it's fairly well accepted that in a small percentage of cats, this cancer will occur. And, Dr. Levy points out, even though this is a small percentage statistically, that's still thousands of cats each year who will be diagnosed with it.
Julie Levy, D.V.M., Ph.D., and Maddie’s Professor of Shelter Medicine, unveiled the results of a study just completed where they looked at the impact of moving feline vaccine injection sites to the tip of the tail.
Tail vaccination allows for a far more effective surgical treatment of any cancer that will occur near the site, Levy says.
And because such treatment is less invasive (thus less expensive), she hopes that it will be something more pet owners would be willing to treat.
Treatment to the tail would also be less disfiguring for the animal - another plus.
One major concern of those participating in the study was how well the injections would be received by the patient! U of F veterinary student Cleon Hendricks, one of the participants in the research study, admitted to some apprehension. He was pleasantly surprised to find that the cats accepted vaccination in the tail just as well as they did in the leg!
UPDATE: We were unaware that a drug had been developed to deliver a six-month systemic flea prevention through injection, but discovered it in the course of researching this article. Please do not accept this for your pet if offered. The drug, called Program, has also been found to cause cancer in cats. Besides, you need to protect your cat for heartworm anyway, and monthly topical treatments that provide that protection will also handle fleas and ticks. 'Nuff said.
National Institutes for Health Article archive
University of Florida's College of Veterinary Medicine New Release
AVMA on the web
U of Fla Small Animal Hospital, on vaccination and sarcomas
Current studies on tail vaccination in cats
Vaccines - do our cats really need them?
Eigner, Diane R. "Feline Vaccine Guidelines". The Winn Feline Foundation. Retrieved 2006-08-27.
Cleon Hendrick's article on his experience participating in the study
Centers for Disease Control: About Adjuvants
Information on Vaccine-Associated Sarcomas