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