Epidermal growth factor in breast cyst fluid: Relationship with intracystic cation and androgen conjugate content

In recent years, several studies focused on the biochemical analysis of breast cyst fluid composition. It has been shown that breast cysts lined by apocrine epithelium contain higher levels of potassium and dehydroepiandrosterone-sulphate as compared to cysts lined by flattened cells, and that women with apocrine cysts are more likely to develop breast cancer. In the present study, we measured the intracystic levels of sodium (Na⁺), potassium (K⁺), dehydroepiandrosterone-sulphate (DHEA-S), and epidermal growth factor (EGF), a factor which could play a role in the autocrine or paracrine control of breast cancer cell growth as recently proposed by some investigators. Breast cyst fluids obtained by fine-needle aspiration from 86 women with gross cystic breast disease were assayed. On the basis of the relative intracystic concentrations of Na⁺ and K⁺ two main classes of cysts were defined. An arbitrary cut-off value of 3 for the Na⁺/K⁺ ratio seemed adequate to separate these two types of cysts. An inverse relationship was found between the Na⁺/K⁺ ratio and DHEA-S concentration, median levels of the androgen conjugate being 3615 μg/dl in Na⁺/K⁺ +/K⁺ >3 cysts (P <0.001). EGF levels were found to be significantly higher in Na⁺/K⁺ +/K⁺ >3 cysts: 103.26 ng/ml versus 57.22 ng/ml, respectively (P +/K⁺ >3 cysts, while in the Na⁺/K⁺ +/K⁺