33rd Annual Scientific Meeting proceedings

Feline mammary tumours are the most frequent neoplasm causing death in cats and the third most commonly diagnosed neoplasm following lymphohematopoietic and skin tumors and account for 12% of all neoplasms in cats. Mammary neoplasms occur predominantly in middle-aged to older female cats with a mean age of 10 to 12 years. Feline mammary neoplasms, typically classified according to the World Health Organization criteria (table 1), are usually represented by in situ or invasive carcinomas. Unfortunately, 80-90% of feline mammary tumors are malignant and entail rapid progression and metastasis at an early stage. Feline mammary carcinomas (FMC) commonly metastasize to lung and regional lymph nodes. The gold standard first-line treatment for FMC is surgery (staged bilateral radical mastectomy), regardless of the size of the tumour, since this approach is associated with longer disease-free intervals. Reported survival times for FMC range from 10-16 months, where several prognostic factors can influence the overall survival. Tumour size, lymph node involvement, histologic grade, and lymphovascular invasion are described as the most commonly described prognostic factors. Reported median survival time for stage IV mammary carcinomas is around 2 months. A guarded prognosis is also associated with grade 3 tumours, with 100% of death in the one-year post-surgical analysis and 80% of death for positive lymphovascular invasion.

Based on this aggressive biological behaviour and high metastatic rate, adjuvant chemotherapy is recommended, although its clinical benefit is still unclear. Only retrospective studies investigated adjuvant therapeutic approaches. Randomized prospective trials are required to clarify the effectiveness of adjuvant chemotherapy treatment.

This presentation will compare the most recent published scientific knowledge and the most common approaches performed in clinic to treat FMC (Data collected via an online survey).

Table 1. Modified World Health Organization Clinical Staging

System for Feline Mammary Tumors

WITHROW AND MACEWEN’S SMALL ANIMAL CLINICAL ONCOLOGY, ed 4, St Louis, 2077, Saunders