Response

Extract

Zaviačič and Ablin want to use the term “female prostate” to describe what is widely known as the Skene's glands and ducts, a terminology that I do not oppose. In addition to the literature provided, others have also made such suggestions in the past (1). One of the biochemical similarities between male prostate tissue and Skene's gland tissue is the expression of prostate-specific antigen (PSA). Indeed, PSA has been immunohistochemically localized in Skene's gland tissue by a number of investigators. However, it should be pointed out that female tissue other than the Skene's gland can produce PSA. Normal female breast epithelial cells produce relatively large amounts of PSA and secrete it into the lumen of the mammary ducts. A small portion of this PSA escapes into the general circulation and can be measured with highly sensitive techniques.

A misconception in the letter by Zaviačič and Ablin is the notion that PSA is expressed by breast tumors as part of the neoplastic transformation process. Originally, our group had discovered PSA expression in a subset of breast tumors that were more frequently steroid hormone receptor-positive (2). Subsequent studies have indicated that PSA is expressed not only by breast tumors but by normal and hyperplastic breast tissue as well (3). In fact, hyperplastic breast tissue contains more PSA than either normal or cancerous breast tissue, and the same applies to the serum PSA in women with these conditions (4). Importantly, PSA has been found in all breast secretions, including breast cyst fluid, the milk of lactating women, and nipple aspirate fluid. The concentration of PSA in nipple aspirate fluid can reach levels up to 3000 mg/L, about 1000 times higher than in male serum (5). PSA concentration is higher in the nipple aspirate fluid of women with no risk for breast cancer and significantly reduced in breasts with cancer (5). We thus conclude that PSA is a normal secretory product of the breast epithelial cells. Some well-differentiated and receptor- positive breast tumors retain the ability to produce PSA.