EGFR and breast cancer: Breast adipose tissue functions in oestrogen biosynthesis and high local levels of oestrogen are related to breast cancer development and progression.153 Oestrogen upregulates growth factors such as epidermal growth factor receptor and Akt phosphorylation, sustaining breast cancer growth.154 Oestrogen plays a role in the increased aggressiveness of breast cancer in obese individuals.155 Adipose-derived stem cells isolated from abdominal adipose tissue of those with a body mass index >30 enhance breast cancer cell line proliferation and tumorigenicity in vitro and in vivo.