Research Updates: Investigating the Impact of Vaccine Administration Site Changes in Cats DVM360 October 1, 2009 by Erika Meler and Barrak Pressler http://veterinarymedicine.dvm360.com.../detail/632167

"The study's results also imply that the rabies vaccine may be the most oncogenic. After 1996, when specific locations could be associated with specific vaccines, the right rear limb, which is the recommended site of rabies vaccination, was the most common site of injection-site sarcomas. "

Oncogenic: Causing or tending to cause the formation and development of tumors.