ASSOCIATION OF CYST TYPE WITH RISK-FACTORS FOR BREAST-CANCER AND RELAPSE RATE IN WOMEN WITH GROSS CYSTIC-DISEASE OF THE BREAST

The concentration of potassium (K+) and sodium (Na+) was measured in b reast cyst fluid (BCF) from 611 cysts > 3 ml aspirated in 520 women wi th gross cystic disease of the breast. These women were enrolled, from 1983 on, in a cohort study aimed at assessing the relationship betwee n cyst type, as defined by the K+/Na+ ratio in BCF, and the risk of br east cancer. The inverse relationship between K+ and Na+ and the bimod al distribution of the K+/Na+ ratio in BCF were confirmed. Type I cyst s were defined as cysts with a K+/Na+ > 1.5 in BCF. Among women with t ype I cysts, a higher proportion of women with one or no births, of wo men with a history of apocrine cysts, of current smokers, and of women who do not drink coffee was found, as compared to women with other ty pes of cysts. The risk of cyst relapse was significantly higher among women with type I cysts than among women with other types of cysts and among women with multiple cysts at presentation. These findings indic ate that type I BCF is a marker of "active" gross cystic disease of th e breast and suggest that it may be associated with increased breast c ancer risk.