Canine and Feline Spontaneous Mammary Tumours as Models of Human Breast Cancer

Abstract

The frequency of cancer presents an increasing trend in humans and companion animals, and despite recent advances in diagnosis and treatment, it remains a major cause of morbidity and mortality in human and veterinary medicine. The epidemiological and clinicopathological similarities between spontaneous tumours of companion animals and their human counterparts make them suitable natural models for human cancer research. Moreover, the faster progression of cancer in dogs and cats in comparison with humans, associated with the shorter life span of companion animals, enables faster data retrieval than in human malignancies. Furthermore, the health effects associated with exposure to environmental hazardous materials, including cancer, occur similarly in companion animals and humans; consequently, in an epidemiological context, dogs and cats can also be useful as sentinels of human malignancies. For these reasons, comparative oncology, which can be defined as the study of spontaneous cancers in animals as models for human disease, has gained increasing importance over the last decades. Breast cancer represents the most prevalent cancer among women worldwide and the leading cause of cancer-related mortality in women. Mammary gland tumours are also among the most frequent tumours in female dogs and cats. Canine and feline mammary tumours present similar incidence, relative age of onset, risk factors, biological behaviour, metastatic pattern, histological, molecular, and genetic features, and response to therapy to human breast cancer; thus, they are recognized as suitable natural models for human breast cancer studies. The comparative “One Health” approach allows advances in knowledge of the diseases in order to obtain an improvement in clinical outcomes for affected humans and animals.