4.1. Tumour Model

The BALB/c 4T1 murine breast cancer model is a commonly used in vivo syngeneic model of aggressive breast cancer, typically resulting in rapid metastatic spread similar to human disease. 4T1 cells are resistant to 6-thioguanine, enabling metastatic cells present in distant organs to be quantified using tissue culture techniques [33]. Spontaneous metastasis of tumour cells in this model occurs on average 8 days following inoculation of 4T1 tumour cells into the mammary fat pad. In this experiment, tumour excision was performed after 7 days, typically before development of metastatic disease, thereby allowing the effect of perioperative agents on subsequent metastasis to be quantified.