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Injection-Site Sarcomas

Shaw SC, Kent MS, Gordon IK, et al. Temporal changes in characteristics of injection-site sarcomas in cats: 392 cases (1990-2006). Journal of the American Veterinary Medical Association. 2009;234(3):376-380.

A proposed association between vaccinations and tumor formation in cats was first discussed in 1991. Studies since that time have supported a link between injections and the development of sarcomas. Fibrosarcomas are highly invasive and about 1/4 will metastasize. Radical surgery in combination with radiation therapy is required to control these tumors. In 1996, the Vaccine-Associated Feline Sarcoma Task Force (VAFSTF) was formed to identify methods to prevent and treat these tumors. One recommendation was to administer vaccinations to cats in standardized sites, avoiding the interscapular area. The purpose of this study was to evaluate changes in anatomic location and histologic classification of injection-site sarcomas, as well as signalment of affected cats before and after publication of the VAFSTF recommendations. In this retrospective case series, medical records of 392 cats with a diagnosis of sarcoma at a potential injection site were examined. From before to after the publication of the VAFSTF recommendations, the proportions of injection site-sarcomas significantly decreased in the interscapular and thoracic regions. However, proportions of the tumors in other locations significantly increased. Despite the recommendations, a high proportion of tumors still developed in the interscapular region. The researchers concluded that veterinarians are complying with the recommendations to some extent, but should ensure vaccinations are administered as distally as possible on a limb to allow for complete surgical excision should a tumor develop.
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Related articles:
Romanelli G, Marconato L, Olivero D, Massari F, Zini E. Analysis of prognostic factors associated with injection-site sarcomas in cats: 57 cases (2001-2007). J Am Vet Med Assoc. 2008 Apr 15;232(8):1193-9.
>> PubMed Abstract