Radiation therapy as an adjuvant therapy for the treatment of oral melanoma in a dog / A utilização da radioterapia como terapia adjuvante no tratamento do melanoma oral em um cão

ABSTRACT

Background: Canine oral melanoma is highly aggressive, with an infi ltrative and metastatic behavior. The staging scheme for dogs with oral melanoma is primarily based on size, with stage I = 2 cm diameter tumor, stage II = 2 cm to 4 cm diameter tumor, stage III = 4 cm or greater tumor and/or lymph node metastasis and stage IV = distant metastasis. Surgery and radiation therapy are commonly used for local treatment of oral melanoma. Surgery must be aggressive and wide excision, such as partial mandibulectomy or maxillectomy, can be declined by owners. Median survival times for dogs with oral melanoma treated with surgery and chemotherapy is approximately seventeen, fi ve and three months with stage I, II and III disease, respectively. Radiation therapy plays a role in the local treatment of canine melanoma when the tumor is not surgically resectable, the tumor has been removed with incomplete margins and/or the melanoma has metastasized to local lymph nodes without further distant metastasis.Case A dog with stage III oral melanoma was treated with radiation therapy and chemotherapy. The protocol consisted of three 8 gy radiation fractions (days 0, 7 and 21) delivered by an orthovoltage unit. Energy of 120 kV, 15 mA e 2 mm aluminum fi lter were used. Collimator size was 6 x 8 cm and source to skin distance was 30 cm. Dose rate was 187 cgy/ minute delivered at 1 cm tis

RESUMO

Background: Canine oral melanoma is highly aggressive, with an infi ltrative and metastatic behavior. The staging scheme for dogs with oral melanoma is primarily based on size, with stage I = 2 cm diameter tumor, stage II = 2 cm to 4 cm diameter tumor, stage III = 4 cm or greater tumor and/or lymph node metastasis and stage IV = distant metastasis. Surgery and radiation therapy are commonly used for local treatment of oral melanoma. Surgery must be aggressive and wide excision, such as partial mandibulectomy or maxillectomy, can be declined by owners. Median survival times for dogs with oral melanoma treated with surgery and chemotherapy is approximately seventeen, fi ve and three months with stage I, II and III disease, respectively. Radiation therapy plays a role in the local treatment of canine melanoma when the tumor is not surgically resectable, the tumor has been removed with incomplete margins and/or the melanoma has metastasized to local lymph nodes without further distant metastasis.Case A dog with stage III oral melanoma was treated with radiation therapy and chemotherapy. The protocol consisted of three 8 gy radiation fractions (days 0, 7 and 21) delivered by an orthovoltage unit. Energy of 120 kV, 15 mA e 2 mm aluminum fi lter were used. Collimator size was 6 x 8 cm and source to skin distance was 30 cm. Dose rate was 187 cgy/ minute delivered at 1 cm tis