Gross
cystic breast disease is a common condition in women. Women with apocrine
breast cysts (
breast cyst fluid Na+/K+ less than 3) may be at higher risk of
breast cancer than women who have
cysts lined by flattened epithelium (Na+/K+ greater than or equal to 3).
Breast cyst fluid concentrations of
epidermal growth factor were significantly higher in the low
electrolyte ratio group than in the high
electrolyte ratio group (356.2 ng/ml vs 104.1 ng/ml, P less than 0.0003). A negative correlation was obtained between intracystic
epidermal growth factor concentrations and Na+/K+ (rs = -0.666, P less than 0.001). No significant difference was found between the total
oestradiol concentrations in the two
cyst groups. However, the unbound
oestradiol concentrations on a limited number of samples were significantly higher in the low
electrolyte ratio group than in the high
electrolyte ratio group (P less than 0.05). The higher concentrations of
EGF in cyst fluid with Na+K+ less than 3 may explain why women with apocrine
breast cysts may be at increased risk of developing
breast cancer.