Epidermal Growth Factor and Prolactin in Human Breast Cyst Fluid a

Human breast cystic disease is the most common benign breast disease, occurring predominantly in women between age 35 and the menopause.‘ The development of cysts in the breast is the result of a unique pathological secretion from breast epithelial cells which have undergone an apocrine metaplastic transformation. Although breast cysts are not considered in themselves to be precancerous, several studies have shown that women with breast cystic disease have a twoto fourfold increased risk for breast cancer.’-’ Therefore, several investigators have studied composition of breast cyst fluid in an attempt to elucidate the mechanisms of this increased risk. In the last 15 years it has been reported that breast cyst fluid (BCF) contains large amounts of a progesterone and pregnenolone binding protein;6 enzymes; ’ carcinoembryonic antigen;’ androsterone, dehydroisoandrosterone, and their sulfates;’ and estriol conjugates.’ Moreover, the presence of pituitary peptides (luteinizing hormone, follicle-stimulating hormone, growth hormone, thyrotropin stimulating hormone, and prolactin) in BCF has been and it has been observed that dehydroepiandrosterone sulfate (DHAS) and prolactin (hPRL) concentrations in this medium were correlated ~ignificantly.’~ In 1979, a major protein constituent of human breast cyst fluid termed “gross cystic disease fluid protein 15” (GCDFP-15) has been identified, isolated, and characterized by Haagensen ef al. I4 The amino acid structure of this unusual glycoprotein has been recently elucidated from cDNA analysis.”