Prognostic significance of the estrogen-regulated proteins, cathepsin-D and pS2, in breast cancer.

The evaluation of prognostic factors for breast cancers is important for therapeutic decisions both at the time of surgery and during postoperative surveillance. Cathepsin-D (cath-D) is an estrogen inducible aspartyl protease. Studies have demonstrated two biological activities, at an acidic PH, of the protein: a mitogenic and a proteolytic activity; both the growth promoting activity and the extracellular proteolytic activity suggest that cathepsin D (cath-D) may have prognostic significance in breast cancer. Measurement of cath-D in breast tissue, in fact, is highly significant in predicting recurrence as well as disease free interval and overall survival. The pS2 is a small cysteine-rich protein specifically expressed under estrogen transcriptional control. Expression of the pS2 protein in breast carcinoma is a useful guide to prognosis and response to tamoxifen: appropriate adjuvant therapy can be selected on the pS2 status of the tumor; patients with pS2 expression had better overall survival and a longer survival time after the first recurrence than those without pS2 expression. For these reasons, these two new prognostic markers could be suggested as habit factors in breast cancer.