Radiation Therapy and Surgery for Fibrosarcoma in 33 Cats

Abstract

Thirty-three cats with histologically confirmed fibrosarcomas were treated with radiation therapy followed by surgery. The median (95% confidence interval) disease free interval and overall survival were 398 (261,924) and 600 (lower limit 515) days, respectively. There were 19 treatment failures; 11 cats had only local recurrence, 4 cats developed metastatic disease, 3 cats had local recurrence followed by metastasis, and 1 cat developed simultaneous local and distant disease. Twelve cats are alive and disease free. Two cats died without evidence of treatment failure. The presence of tumor cells at the margin of resected tissue after radiation was the only variable which influenced treatment success. The median (95% confidence interval) disease free interval in 5 cats with tumor cells at the margin of the resected specimen was 112 (94,150) days versus 700 (lower limit 328) days for 26 cats with negative tumor margins, p < 0.0001. We did not identify a relationship between tumor volume, number of prior tumor excisions, concomitant use of chemotherapy or various descriptors of the radiation therapy technique and disease free interval.

Use of surgery and electron beam irradiation, with or without chemotherapy, for treatment of vaccine-associated sarcomas in cats: 78 cases (1996–2000)

“…7 Vaccine-associated sarcomas have a higher recurrence rate and higher metastatic potential than do nonvaccine-associated sarcomas. 4,[8][9][10] Recurrence rates following surgical excision reportedly range from 30 to 70%, even with administration of adjuvant treatment such as radiation therapy and chemotherapy, and rates of metastasis range from 10 to 25%. 4,[8][9][10][11][12] The median disease-free interval following surgery alone ranges from 94 days to > 16 months.…”

Vaccine-associated feline sarcomas

“…Despite the combination of aggressive surgery and radiation therapy, however, treatment will fail in many patients. 29,b,c Vaccine-associated feline sarcomas are somewhat sensitive to a variety of chemotherapeutic agents such as doxorubicin, carboplatin, mitoxantrone, and cyclophosphamide. However, the addition of chemotherapy to radiation therapy and surgery has only modestly prolonged disease-free intervals.…”

Description of a Feline Injection-Site Fibrosarcoma with Metastasis in the Cerebellum

“…Thus, a survival rate of up to 576 days after surgery was reported [4,12]. However, even after a wide surgical excision, the relapse rate of FISS is high (45%) [2,13].…”