Vaccine-associated sarcoma
radiation therapy for cats
in Florida.

Surgery and radiation,
together.

Vaccine-associated sarcoma infiltrates beyond its visible margins — invading muscle, fascia, and adjacent tissue far beyond what can be seen or palpated. This is why surgery alone is often followed by recurrence. Radiation treats the microscopic disease beyond the surgical margins, reducing the risk of local recurrence.

VAS is associated with an inflammatory response at injection sites — most commonly vaccines, and rarely other injected materials. The resulting sarcoma is biologically aggressive: it grows rapidly, extends along fascial planes, and can reach surgical margins even with aggressive resection. Current guidelines recommend wide surgical margins, which are often difficult to achieve without significant morbidity.

Pre-operative vs. post-operative radiation

Neoadjuvant (pre-operative) radiation reduces tumor volume before surgery, potentially allowing wider margins and sterilizing the invasive periphery. Post-operative (adjuvant) radiation therapy targets the surgical bed where microscopic residual disease persists. Both approaches are used; the sequence depends on tumor size, location and surgical planning. Dr. DiBernardi discusses the optimal sequence for each case individually.

What CT reveals — and why it matters

CT of the primary site and thorax is essential before treatment. CT defines the true extent of tumor infiltration — often revealing invasion far beyond palpable boundaries — and screens for pulmonary metastasis. This information directly impacts surgical planning, radiation field design, and prognosis.