Background: Breast cancer represents one of the most significant health risks in the human female population due both to its frequency and metastatic potential. Current therapies, while improving the overall survival rate of women with mammary neoplasias, have not eliminated this disease as an important cause of morbidity and mortality.
Materials and methods: We have investigated transplantation of a feline mammary adenocarcinoma cell line into fetal cats as a model of human metastatic breast cancer. Fetal cats injected in utero with an allogeneic mammary adenocarcinoma cell line were born with palpable masses at the site of injection and developed widespread metastases over the following 6-10 weeks. Tumor foci were seen most commonly in the lung and in the local tissues adjacent to the primary injection site. This distribution of metastases mimics that seen in human breast cancer. Thus, in utero transplantation in cats is a reproducible experimental model of metastatic breast cancer in women.