VAS Diagnosis and Management Guidelines Three most important considerations: Consult with an oncologist with experience in treating VAS prior to initiating therapy. * Or at least consult with a vet/specialist experienced in VAS. A mass that develops at a previous injection site should be considered malignant until proven otherwise. * Incomplete surgical removal of a sarcoma is the most common cause of treatment failure. * In addition, the method of performing a biopsy can also jeopardize prognosis. Diagnosis A complete medical history including vaccination history and physical exam should be performed. A lesion should be fully assessed and aggressively treated if any of the following criteria is met: * Persists more than 3 months post-injection, Is larger than 2 centimeters in diameter, Is increasing in size after one month post-injection. A diagnostic biopsy is recommended prior to surgical incision. Biopsy should be incisional (small part of mass) rather than excisional (the whole mass). **** All tissues affected by the biopsy should be removed by subsequent surgery if VAS is confirmed. Treatment Surgery Surgery is the single most important component of successful therapy. ** If possible, surgery should be performed by a board certified surgeon or trained surgeon as studies have shown that this increases the chances for success/survival. Performing the first surgery in prescribed manner is the best chance for favorable prognosis. Aggressive surgical resection is essential. All previous incisional biopsy sites should be completely excised. ** En bloc (entire tumor and margins removed as one piece) removal of tumor together with wide and deep 3 centimeter margins of normal tissue should be performed. ** VAS Task Force recommends removing at least a 2 cm margin in all planes. * Radiation therapy Can be used in both pre-operative and post-operative settings. *** Radiation prior to surgery can help shrink the tumor which may allow for a less radical surgery with better outcomes. Best results are obtained in conjunction with surgery. Radiation therapy alone is not recommended to treat vaccine-associated sarcomas if the intent is cure. *** Chemotherapy Can be used in both pre-operative and post-operative settings. May be used in conjunction with surgery and/or radiation. Chemotheraphy alone should not be considered for definitive therapy. *** references: * Vaccine Associated Feline Sarcoma Task Force (1999) “Vaccine-Associated Feline Sarcoma Task Force Guidelines, Diagnosis and Management of Suspected Sarcomas” ** World Small Animal Veterinary Association World Congress – Vancouver 2001 – “Vaccine-Associated Sarcomas in the Cat”, Glenna Mauldin, Canada *** Atlantic Coast Veterinary Conference 2001 – “Vaccine-Associated Sarcomas: Diagnosis and Treatment Strategies” Margaret C. McEntee, DVM, DACVIM, DACVR, Cornell University **** Gulf Coast Veterinary Oncology’s Tumor Tidbits. Volume1, Number 8: July 5, 2000, Editor: Dr. Kevin A. Hahn, Gulf Coast Veterinary Oncologists, Houston, TX