Inflammatory carcinoma is the most aggressive variant of invasive mammary cancer in humans and dogs, being characterized by fulminant disease progression and a high mortality rate.1–3 Inflammatory carcinoma represents a distinct disease entity, rather than being part of the spectrum of advanced mammary tumors,1,3–5 and is associated with a high rate of early regional and distant metastases1 and a high incidence of locoregional recurrence if surgery is attempted.6 Accordingly, IC should be considered a systemic disease at the time of initial examination, even if metastases are not identified.7
A diagnosis of IC is made on the basis of clinical and histologic findings. Mammary IC is evident clinically as a rapidly enlarging mammary mass with concomitant signs of inflammation, such as erythema, induration of the mammary gland, warmth, signs of pain, and edema of the extremities. The condition can be mistaken for acute mastitis.2,3 Dermal lymphatic invasion by neoplastic cells is typically observed during histologic examination of affected tissues and represents a critical hallmark of the disease.3,5 Although IC does not refer to a specific histologic type, poorly differentiated or anaplastic carcinoma is usually diagnosed.3
In human medicine, evidence has accumulated to indicate that neoadjuvant systemic chemotherapy followed by mastectomy, radiotherapy, and possibly hormonal therapy offers the most favorable outcome.8 Current induction chemotherapy consists of administration of anthracyclines and taxanes.8 In veterinary medicine, dogs not euthanatized at the time of diagnosis have typically received only palliative medical treatment, such as antimicrobials, glucocorticoids, and NSAIDs, and the outcome of treatment has typically been poor. Identification of high tumor cyclooxygenase concentrations has opened up the possibility of treating IC with cyclooxygenase inhibitors,9 but no clinical follow-up data are currently available. Chemotherapy has been attempted only rarely, and surgical excision is often not an option because of extensive cutaneous involvement and concurrent coagulopathies.6 Regardless of the chosen treatment modality, overall survival time in most dogs with mammary IC does not exceed 30 days.2
Despite the reported unfavorable prognosis for dogs with mammary IC, results of treatment in a large cohort of affected dogs have not, to the authors' knowledge, been reported. The purposes of the study reported here, therefore, were to describe clinical characteristics, treatment, and outcome of dogs with mammary IC and identify patient-, tumor-, and treatment-related factors associated with overall survival time.
SPSS, version 11.0, SPSS Inc, Chicago, Ill.
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