Mast Cell Tumors, Canine - contd.
All mast cell tumors should be treated regardless of their size. The type of
treatment selected depends on the clinical stage, histologic grade, size and location of the tumor. Aggressive, local surgical excision is the primary therapeutic approach; other treatment methods are employed adjunctively, or in certain situations. Establishing a definitive diagnosis and treatment plan prior to instituting therapy is therefore extremely important in dogs with mast cell tumors.
Ideally, the goal of surgery is to remove the entire tumor mass and any tissue surrounding it, including lymph nodes, that may harbor spreading tumor cells. Wide excisional margins, at least three centimeters in all directions, should be obtained where feasible. Excised tissue is submitted to a pathologist for careful histopathologic evaluation. The tissue margins are examined for evidence of incomplete tumor excision.
In cases where the pathologist reports incomplete excision, either additional surgery or radiation therapy may be necessary. If adequate surgical margins are impossible to obtain despite aggressive surgery, radiation should be considered as an additional treatment.
Chemotherapy may be employed if surgery and radiation treatments fail to eliminate all of the tumor cells, or if these local treatment methods are not feasible. Prednisone has been shown to be efficacious in certain cases of mast cell tumors. This response appears to be variable, but complete responses have been demonstrated. Chemotherapy has been partially successful with lomustine (CCNU) and possibly a combination protocol consisting of vinblastine, cyclophosphamide, and prednisone.
For cases where surgery alone, or surgery with radiation therapy, have a good chance of completely eliminating the tumor and any metastatic, or spreading, disease, then these local treatment approaches should be attempted first.
