Wilcock B, Wilcock A and Bottoms K. Feline postvaccinal sarcoma: 20 years later. Can Vet J. 2012; 53: 430-4.
After vaccine-associated sarcomas were first identified in 1991, a large amount of information from histological assessment of these sarcomas along with a wealth of clinical and epidemiological studies culminated in a consensus about many aspects of this disease. This consensus lead to recommendations for profound changes in feline vaccination protocols in the 2 years following the formation of the Vaccine-Associated Feline Sarcoma Task Force in 1996. For example, the recommendations called for more selective use of leukemia vaccination, less frequent vaccination for rabies, and vaccination at distal limb sites that are more amenable to amputation. In addition, it was hoped that introduction of virus-vectored, non-adjuvanted leukemia and rabies vaccines that cause little or no inflammation would further contribute to a gradual decline in disease prevalence. Little long-term evaluation of disease prevalence has been published after recommended changes in feline vaccination protocols.
The authors in this report present prevalence data based on 1,401 feline postvaccinal sarcoma biopsy samples diagnosed out of 11,609 feline skin masses submitted at a single histopathology laboratory (Histovet Surgical Pathology, Guelph, Ontario, Canada) for the 19 year interval from 1992 to 2010. Their results indicate no statistically meaningful change in overall disease prevalence over the past 19 years. In particular, there has been no apparent decrease in overall prevalence in response to vaccination protocol changes initiated in 1996, or in response to introduction of non-adjuvanted rabies vaccine in the year 2000. The authors speculate that failure to detect any meaningful change in disease prevalence is likely due to there not being a significant shift in use from traditional adjuvanted vaccines to the newer virus-vectored non-adjuvanted vaccines. The major barrier for not using the newer vaccines is thought to be their higher cost and annual re-vaccination licensing instead of every 3 or 4 years. [GO]