Outcome of adjuvant chemotherapy with lomustine, vinblastine and chlorambucil on management of canine mast cell tumour of high to intermediate risk

Abstract

In spite of the many available protocols, the use of chemotherapy for the management of canine mast cell tumours (MCT) remains empirical, and there is lack of criteria for the choice of protocol and definition of patients who may benefit from treatment. The objective of this study was to evaluate the outcome of dogs with MCT after adjuvant chemotherapy according to the risk of recurrence or metastasis proposed on the literature. This prospective study included 89 followed up dogs with prognosis assesment including clinical, histological, immunohistochemical and genetic features of canine MCT. Patients were grouped according to risk of recurrence and metastasis and recommended treatment with lomustine followed by chlorambucil if considered at high-risk, or vinblastine followed by chlorambucil if a patient was at intermediate risk. Outcome was defined by disease-free interval (DFI) and overall survival (OS) estimated by Kaplan-Meier curve. Adjuvant lomustine was useful for control of canine MCT of high-risk of recurrence or metastasis, but only when sequentially associated to chlorambucil with a DFI of 686 days and not reached OS.

Diagnosis, Prognosis and Treatment of Canine Cutaneous and Subcutaneous Mast Cell Tumors

“…However, simple protocols with a single chemotherapeutic agent, usually associated with prednisone or prednisolone, have become more popular. Sequential association of these protocols in an adjuvant modality demonstrated increased disease-free interval and survival in high-risk dogs [ 200 ]. Numerous protocols have been described in the literature; however, data on disease-free interval and other important criteria, to compare their effectiveness, are scarce [ 197 ].…”

“…According to the authors, this protocol yielded a worse response than other protocols. However, Horta et al [ 200 ] observed that patients with high-risk MCT (grade 3 or grade 2 with metastasis) treated with the lomustine protocol at a dose of 60–90 mg per m 2 every 21 days, for a total of 3–4 sessions; followed by chlorambucil at a dose of 4–6 mg per m 2 , every 48 h, for 8 weeks, reached a higher disease-free interval (686 days) than those treated only with lomustine at the maximum dose (107 days).…”