Inflammatory mammary cancer (IMC) is a specific type of locally advanced mammary cancer in dogs. It is an uncommon tumor, but the most aggressive type of mammary cancer in female dogs with an extremely poor survival rate. No effective treatment has been reported for dogs with IMC and surgery is not indicated as first option. Based on the different molecular features of this highly angiogenic cancer, new therapies focused on specific targets have been proposed.

The aim of this study was to evaluate the survival time in dogs diagnosed with IMC treated with a multimodal therapy based on an anti-COX-2 drug (firocoxib), a tyrosine kinase inhibitor (toceranib) and an androgen receptor inhibitor (flutamide).

Ten dogs diagnosed with IMC, presented to the Veterinary Teaching Hospital Complutense of Madrid, were included. Diagnosis was based on clinical features (edema, erythema, warmth and firmness in the mammary glands) and histopathological confirmation. Immunohistochemical analysis (Ki-67 index, C-kit, COX-2 and androgen receptor) were performed. Five dogs received palliative treatment (antibiotics, corticoids) (control group or CG) and the other 5 dogs were treated with a combination of firocoxib, flutamide and toceranib (treatment group or TG). One dog of the TG refused treatment with toceranib due to economy matters. Survival time was defined as the time from IMC diagnosis to euthanasia or death of the dog. Age at the time of IMC diagnosis, reproductive status, previous history of mammary tumors and evolution of IMC after treatment were also analyzed. A paired Student's t-test was performed for statistical analysis of parametric variables with an alpha error of 0.05 and chi-square test for no parametric variables.

The mean survival time of dogs of TG was significantly higher than that of CG (34.6±15.0 and 10.6±13.4 days, respectively; p=0.028). Age at the time of IMC diagnosis (10.8±2.7 years in TG and 11.0±1.9 years in CG), reproductive status and immunohistochemical profile were not significantly different between the 2 groups. In TG, a complete remission was obtained in one case, stable disease in 2/5 dogs and progressive disease in 2/5. In TG grade 2 (n=2) and grade 3 (n=1), toxicities were observed after 3–4 weeks, but an increase in quality of life was referred in all cases after the initiation of the treatment.

Despite poor prognosis, the multimodal therapy increases survival time in dogs diagnosed with IMC with an adequate quality of life.

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