Enterolactone in breast cyst fluid: correlation with EGF and breast cancer risk.

The purpose of our study was to investigate whether enterolactone does accumulate into breast cyst fluid and whether it correlates with breast cancer risk. We included 258 women who had at least one cyst aspiration and known intracystic cation and epidermal growth factor (EGF) concentration values. For 191 of such women serum aliquots were also available. The median value of serum enterolactone was 17 nM/l (range 1-140 nM/l). The median intracystic level of enterolactone was much higher (63 nM/l, range 0-872 nM/l) and was significantly higher in type I cysts (p = 0.000). This cyst type contained also significantly higher levels of EGF (p = 0.000). A direct relationship was found between serum and cyst fluid enterolactone levels (p = 0.000) and between cyst enterolactone and EGF levels (p = 0.03), the latter correlation being evident especially in type II cysts. Twelve patients in the cohort of women were found to have developed a breast cancer. After univariate analysis breast cancer risk was associated with cyst type and especially with EGF concentration. No association was evident for enterolactone concentration. However, enterolactone concentration appeared to significantly decrease the risk of patients with high EGF concentrations. Our results show that enterolactone does accumulate in breast cysts, and that it modulates the risk related to the intracystic level of EGF, which is confirmed to be a strong predictor of breast cancer risk.