Epidermal growth factor levels in human breast cyst fluid.

Epidermal growth factor (EGF) seems to modulate the in vitro and in vivo growth of normal and neoplastic breast cells. We determined, by a radio-receptor assay, EGF levels in cyst fluid and in plasma of patients with gross cystic disease of the breast. The mean levels of EGF were lower in plasma than in breast cyst fluid (BCF) (p less than 0.001). In BCF of apocrine cysts we found higher EGF levels than in flattened cysts (p less than 0.001). The EGF content of apocrine BCF seems to be under sex steroid hormone control, being higher in reproductive age than in post menopause (p less than 0.05). Since it has been reported that patients with apocrine cysts are at a greater risk of developing breast cancer, we hypothesize that the high EGF concentration in apocrine BCF may play a role in the autocrine breast cyst epithelium growth control and neoplastic transformation.