December 12, 2017

A Chance to Cut — Vaccine-associated Fibrosarcoma

There has been a considerable amount of data disseminated regarding vaccineassociated fibrosarcoma in cats. The increasing incidence of this aggressive tumor on typical vaccine locations and the fact that tumors are often found to contain material identical to adjuvant used in vaccines, makes this an important disease from the perspective of prevention and treatment.

Minimize unnecessary vaccinations.
Consider vaccinating on distal hindlimbs (amputation is more likely to afford a cure.)

There is enough experience now with this locally extremely aggressive tumor to offer treatment recommendations.
1. Early recognition; firm nodules in locations typically used for vaccination.
2. Needle aspirate or needle biopsy to diagnose.
3. Radical en bloc resection (or amputation)
When carried out appropriately, this entails major skin and muscle resection as well as underlying bone resection (i.e.: removal of dorsal spinous processes or partial scapulectomy for dorsal interscapular tumors).

4. Radiation therapy to follow surgery
Appropriately planned and marked surgical margins assist with radiation planning.

5. Chemotherapy

Take home message:
The likelihood for cure is greatest after early recognition and the first surgery. After recurrence, the chance for cure even with surgery, radiation and chemotherapy is grave. These are not “lumpectomies” and must be treated aggressively to optimize the outcome.

Lara Rasmussen, DVM, MS
Diplomate, American College of Veterinary Surgery