Presence of epidermal growth factor receptor in breast smears of cyst fluids: relationship to electrolyte ratios and pH concentration.

The purpose of this study was to evaluate and correlate different high risk factors in breast cysts to produce a more accurate prognosis. We considered the cytology of the lining epithelium (apocrine or flattened), the Na+/K+ ratio (less than 3; greater than or equal to 3), the pH (lower, equal, or higher than 7.30), and the EGFr (present or not) in an attempt to reach better prognoses and diagnoses by evaluating more than one risk factor. Our material of 40 macrocysts consisted of 23 simple cysts with flattened epithelium and 17 complex cysts with apocrine or hyperplastic epithelium. In the simple cysts, the Na+/K+ ratio was greater than or equal to 3, while in the complex cysts the Na+/K+ ratio was, in all cases but one, less than 3. The pH was not significantly lower than neutral in the complex cysts. The EGFr was detected in 5 of 23 simple cysts and in 12 of 17 complex cysts. In conclusion, reaction of EGFr in smears of cyst fluids with the low intracystic electrolyte ratios may provide an explanation of why women with apocrine metaplasia or epithelial hyperplasia may be at higher risk of breast cancer than women with cysts which are lined by flattened epithelium.