+ Biologic Behavior
- 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 Behavior
- 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