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Radiation treatment for incompletely resected soft-tissue sarcomas in dogs

Josephine A. McKnightThe Animal Medical Center, 510 East 62nd St, New York, NY 10021.

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 DVM
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G. Neal MauldinDepartment of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803.

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 DVM, DACVIM, DACVR
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Margaret C. McEnteeDepartment of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, CA 95616.

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 DVM, DACVIM, DACVR
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Karelle A. MeleoVeterinary Oncology Services, 22226 Hwy 99, Edmonds, WA 98020.

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Amiya K. PatnaikThe Animal Medical Center, 510 East 62nd St, New York, NY 10021.

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 BVSc, MVSc

Abstract

Objective—To evaluate efficacy of radiation for treatment of incompletely resected soft-tissue sarcomas in dogs.

Design—Prospective serial study.

Animals—48 dogs with soft-tissue sarcomas.

Procedure—Tumors were resected to < 3 cm3 prior to radiation. Tumors were treated on alternate days (three 3-Gy fractions/wk) until 21 fractions had been administered. Cobalt 60 radiation was used for all treatments.

Results—Five-year survival rate was 76%, and survival rate was not different among tumor types or locations. Four (8%) dogs developed metastases. Eight (17%) dogs had tumor recurrence after radiation. Development of metastases and local recurrence were significantly associated with reduced survival rate. Median survival time in dogs that developed metastases was 250 days. Median disease-free interval for all dogs was 1,082 days. Median time to recurrence was 700 days. Dogs that developed recurrence after a prolonged period responded well to a second surgery. Acute radiation toxicosis was minimal; osteosarcoma developed at the radiation site in 1 dog.

Conclusion and Clinical Relevance—An excellent long-term survival rate may be achieved by treating soft-tissue sarcomas in dogs with resection followed by radiation. Amputation is not necessary for longterm control of soft-tissue sarcomas in limbs. Development of metastases and recurrence of local tumors after radiation treatment are associated with decreased survival rate. Acute and delayed radiation toxicosis was minimal with the protocol used in this study. (J Am Vet Med Assoc 2000;217:205–210)

Abstract

Objective—To evaluate efficacy of radiation for treatment of incompletely resected soft-tissue sarcomas in dogs.

Design—Prospective serial study.

Animals—48 dogs with soft-tissue sarcomas.

Procedure—Tumors were resected to < 3 cm3 prior to radiation. Tumors were treated on alternate days (three 3-Gy fractions/wk) until 21 fractions had been administered. Cobalt 60 radiation was used for all treatments.

Results—Five-year survival rate was 76%, and survival rate was not different among tumor types or locations. Four (8%) dogs developed metastases. Eight (17%) dogs had tumor recurrence after radiation. Development of metastases and local recurrence were significantly associated with reduced survival rate. Median survival time in dogs that developed metastases was 250 days. Median disease-free interval for all dogs was 1,082 days. Median time to recurrence was 700 days. Dogs that developed recurrence after a prolonged period responded well to a second surgery. Acute radiation toxicosis was minimal; osteosarcoma developed at the radiation site in 1 dog.

Conclusion and Clinical Relevance—An excellent long-term survival rate may be achieved by treating soft-tissue sarcomas in dogs with resection followed by radiation. Amputation is not necessary for longterm control of soft-tissue sarcomas in limbs. Development of metastases and recurrence of local tumors after radiation treatment are associated with decreased survival rate. Acute and delayed radiation toxicosis was minimal with the protocol used in this study. (J Am Vet Med Assoc 2000;217:205–210)