[3] In 1993, a causal relationship between VAS and administration of aluminium adjuvanted rabies and FeLV vaccines was established through epidemiologic methods, and in 1996 the Vaccine-Associated Feline Sarcoma Task Force was formed to address the problem and promote research.
Several of the tumors were located in common injection sites and had similar histologic features to VAS in cats.
[10] Fibrosarcoma is the most common VAS; other types include rhabdomyosarcoma, myxosarcoma, chondrosarcoma, malignant fibrous histiocytoma, and undifferentiated sarcoma.
[1] X-rays are taken prior to surgery because about one in five cases of VAS will develop metastasis, usually to the lungs but possibly to the lymph nodes or skin.
[3] The expression of a mutated form of p53, a tumor suppressor gene, is found commonly in VAS and indicates a poorer prognosis.
Also, vaccines should be given in areas making removal of VAS easier,[15] namely: as close as possible to the tip of the right rear paw for rabies, the tip of the left rear paw for feline leukemia (unless combined with rabies), and on the right shoulder—being careful to avoid the midline or interscapular space—for other vaccines (such as FVRCP).
[16] There have been no specific associations between the development of VAS and vaccine brand or manufacturer, concurrent infections, history of trauma, or environment.