Veterinary Society of
Surgical Oncology

ORAL FIBROSARCOMA

Biologic Behaviour

  • oral FSA is the 3rd most common canine oral tumor with an incidence of 7.5%-25.0%
  • median age 7.3-8.6 years, but 25% dogs are < 5 years
  • sex predisposition: ± male with a male-to-female ratio of 1.4-2.8:1
  • site predilection: gingiva (usually on maxillary arcade between the canine and carnassial teeth) (56%-87%), hard palate (7%-17%), and buccal or labial mucosa (4%-22%)
  • gross appearance: flat, firm, ulcerated, multilobulated, and deeply attached
  • locally invasive into the gingiva and bone with local tumor recurrence after surgical excision common
  • 60%-65% dogs have radiographic evidence of bone involvement
  • metastasis to the regional lymph node in 19%-22% and lungs in 6%-27% dogs

Treatment

  • surgical techniques: mandibulectomy and maxillectomy
  • FSA is poorly responsive to radiation therapy and chemotherapy
  • radiation therapy can be used alone or in combination with surgical excision, but is considered palliative
  • no known effective chemotherapeutic agent, but doxorubicin and piroxicam may have some effect

Prognosis

  • local control is more important than metastatic disease with local recurrence the most common cause of death
  • high-grade anaplastic oral FSA have a higher metastatic potential than low-grade FSA
  • MST for both mandibular and maxillary oral FSA following surgical resection: 11 months with 12-month survival rate 25%-40% and local recurrence rate 46%
  • MST following mandibulectomy: 10-12 months with 12-month survival rate 50% and local recurrence rate 10%
  • MST following maxillectomy: 11-12 months with 12-month survival rate 21% and local recurrence rate 33%
  • radiation therapy: MST 6-26 months
  • radiation therapy and hyperthermia: 12-month survival rate 50%

HISTOLOGICALLY LOW-GRADE BUT BIOLOGICALLY HIGH-GRADE FIBROSARCOMA

Biologic Behaviour

  • histologically low-grade but biologically high-grade FSA occurs predominantly in the maxilla (72%) of large breed dogs, especially Golden Retrievers (54%)
  • histological appearance is benign (i.e., fibroblast proliferation with abundant production of collagen) and can often be interpreted as fibroma or low-grade FSA
  • 72% dogs have radiographic evidence of bone lysis
  • metastasis to the regional lymph node in 20% and lungs in 12% dogs

Treatment

  • surgical treatment: mandibulectomy and maxillectomy
  • radiation therapy can be used alone or in combination with surgical excision, but is considered palliative
  • no known effective chemotherapeutic agent, but doxorubicin and piroxicam may have some effect

Prognosis

  • survival depends on early diagnosis and aggressive treatment
  • prolonged survival times can be achieved with surgery, surgery and radiation therapy, radiation therapy alone, and radiation therapy and hyperthermia

ORAL FIBROSARCOMA

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