Fibrosarcoma

Fibrosarcoma is a type of tumor that arises out of bone and connective tissue in dogs and cats, but these tumors are far more common in dogs than in cats. In the canine, fibrosarcomas most commonly arise from the mouth from inside the jaw bone. In cats, fibrosarcomas arise most commonly from a point on the body where a vaccine or other injection has previosly been given, giving rise to the characterization: vaccine induced fibrosarcoma. The main associated vaccines in the development of feline vaccine induced fibrosarcoma have been rabies and feline leukemia. However, the overall incidence of these types of tumors are considered to be quite rare. It is an overwhelmingly accepted notion that the risk of disease for unvaccinated cats far outweighs the danger of developing vaccine induced fibrosarcoma at a vaccine site.

Years of research of firbocsarcoma incidence has caused much of the veterinary community to reconsider them as “injection induced” firbosarcomas. This is because many studies have found a very close incidence of fibrosarcoma in control groups that received only sterile water injections, to cats that have been life long vaccinated. So it seems that the mere act of giving a cat an injection can lead to cellular mutations that cause fibrosarcomas. This is why it has become a widely accepted practice, when possible, to administer all injections in the extremities and not on the trunk. With a low incidence of matestasis (see below), if a cat were to develope an injection induced fibrosarcoma, amputation of the affected limb is more often than not life saving.

Fibrosarcomas have a low incidence of metastasis (spread to other tissues). While they do not tend to metastasize, they are invasive tumors that root themselves deeply in underlying tissue, causing destruction of underlying tissue as they grow.

Treatment for fibrosarcoma is primarily surgical, with success dependent upon the ability of the surgeon to resect the entire tumor. This is largely dependent on how deeply rooted the tumor is, and what anatomical location the tumor arises from. Fibrosarcomas that arise from the mouth and nasal sinuses pose much greater challenge surgically resecting than those arising from the body. However, deeply rooted and/or large fibrosarcomas can be very difficult to completely surgically resect from any location on the body due to sensitive anatomical structures of inability to close such a large resultant defect. For this reason, surgery often has to be augmented with radiation and chemotherapy to offer the best possible prognosis.