Practical Matters: Consider cross-sectional imaging before surgery for feline injection-site sarcomas

Injection-site sarcomas are associated with high recurrence rates, even with wide surgical excision. The strongest prognostic factor for survival after excision is the state of the surgical margin: Cats with tumor-free margins have significantly longer survival times than do cats with dirty margins (> 16 months vs. 9 months, respectively).1 Conservative (marginal, debulking) surgeries are strongly discouraged for feline injection-site sarcomas. The median time to first tumor recurrence is significantly shorter with a marginal first excision (79 days) than with a radical first excision (325 days).2

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Cross-sectional imaging with computed tomography (CT) or magnetic resonance imaging (MRI) before any surgical intervention is strongly recommended to accurately identify which cats will likely benefit most from surgery. This imaging helps define the gross extent of the tumor and aids in planning the extent of the resection.3 A study performed at Cornell University found that the volume of tumor detected by using CT was, on average, twice the size of the tumor detected by physical palpation and measured with calipers.4 The disease-free interval has also been shown to be significantly shorter when the surgery is performed by a general practitioner rather than a board-certified surgeon.2 This finding likely reflects surgeon expertise and access to advanced imaging modalities, such as CT or MRI.

Amy K. LeBlanc

When evaluating a cat with a possible injection-site sarcoma, practitioners should consult a board-certified surgeon with access to advanced imaging modalities and an oncologist for treatment options, which may include radiation therapy, chemotherapy, or other therapies in addition to radical surgical excision.

Amy K. LeBlanc, DVM, DACVIM (oncology)

Department of Small Animal Clinical Sciences

College of Veterinary Medicine

The University of Tennessee

Knoxville, TN 37996

REFERENCES

1. Davidson EB, Gregory CR, Kass PH. Surgical excision of soft tissue fibrosarcomas in cats. Vet Surg 1997;26(4):265-269.

2. Hershey AE, Sorenmo KU, Hendrick MJ, et al. Prognosis for presumed feline vaccine-associated sarcoma after excision: 61 cases (1986-1996). J Am Vet Med Assoc 2000;216(1):58-61.

3. Lidbetter DA, Williams FA, Krahwinkel DJ, et al. Radical lateral body-wall resection for fibrosarcoma with reconstruction using polypropylene mesh and a caudal superficial epigastric axial pattern flap: a prospective clinical study of the technique and results in 6 cats. Vet Surg 2002;31(1):57-64.

4. McEntee MC, Page RL. Feline vaccine-associated sarcomas. J Vet Intern Med 2001;15(3):176-182.