Mixed tumors of the canine mammary glands: Evaluation of prognostic factors, treatment, and overall survival

Mixed tumors are the most frequent mammary gland neoplasms in bitches; however, studies that thoroughly describe their clinicopathological data, treatment approaches, and the survival of bitches with mixed tumors are scarce. This study evaluated the epidemiological and clinicopathological data, prognostic factors, and therapeutic approaches for bitches with mixed tumors. In all, 162 benign mixed tumors, 682 carcinomas in mixed tumors, and 60 carcinosarcomas were included. Regarding tumor size, T(3) lesions were predominantly associated with carcinosarcomas, while T(1) and T(2) lesions occurred more frequently in benign mixed tumors and in carcinomas in mixed tumors. Based on clinical staging, most bitches with benign mixed tumors presented with stage I tumors; 92% of bitches with carcinomas in mixed tumors presented with stage I–III tumors, while 8% presented with stage IV–V tumors; and 70% of bitches with carcinosarcomas presented with stage I–III tumors, while 30% presented with stage IV–V tumors. Surgery was curative for bitches with benign mixed tumors and for those with stage I–III carcinomas in mixed tumors. Combination therapy in bitches with carcinomas in mixed tumors (IV–V) and carcinosarcomas resulted in a higher overall survival compared with bitches who underwent surgery only. Carcinosarcomas presented higher relapse rates and distant metastases than carcinomas in mixed tumors did.