Prostatic acid phosphatase in breast cyst fluid.

Prostatic Acid Phosphatase (PAP) is mostly found in the epithelial cells and secretions of the prostate gland. It has also been found to be present in several tissues and biological fluid. Gross cystic breast disease is the commonest benign breast condition and several studies have shown that women with palpable breast cysts may have a higher risk of developing breast cancer. There are two types of breast cyst and women with apocrine breast cyst may have a higher risk of developing breast cancer than women with breast cysts lined by flattened epithelium. The growth inhibitory effect of transforming growth factor beta (TGF-beta) on epithelial cells suggests a potential protective role in breast cancer. TGF-beta is secreted as a high molecular weight complex in a biologically inactive or latent form and activation of TGF-beta is necessary for the exertion of its effects on target cells. Prostate specific antigen (PSA) has been found in breast cyst fluid (BCF) and it may have a protective effect on the development of several carcinomas by activating TGF-beta. As a similar molecule to PSA, PAP may also involve in this mechanism. We investigated the presence of PAP in two groups of BCF using an ELISA kit. PAP was found to be present in BCF but there was not a statistically significant difference between the two cyst groups. The presence of PAP in BCF may suggest its possible role in the development of breast cancer from cystic breast diseases. A possible role of PAP on TGF-beta activation needs further investigation.