Expression of prostate-specific antigen (PSA) correlates with poor response to tamoxifen therapy in recurrent breast cancer

Prostate-specific antigen (PSA) is a serine protease which may play a role in a variety of cancer types, including breast cancer. In the present study , we evaluated whether the lever of PSA in breast tumour cytosol could be a ssociated with prognosis in primary breast cancer, or with response to tamo xifen therapy in recurrent disease. PSA levels were determined by enzyme-li nked immunosorbent assay (ELISA) in breast tumour cytosols, and were correl ated with prognosis in 1516 patients with primary breast cancer and with re sponse to first-line tamoxifen therapy in 434 patients with recurrent disea se. Relating the levels of PSA with classical prognostic factors, low lever s were more often found in larger tumours, tumours of older and post-menopa usal patients, and in steroid hormone receptor-negative tumours. There was no significant association between the levels of PSA with grade of differen tiation or the number of invoked lymph nodes. In patients with primary brea st cancer, PSA was not significantly related to the rate of relapse, and a positive association of PSA with an improved survival could be attributed t o its relationship to age. In patients with recurrent breast cancer, a high lever of PSA was significantly related to a poor response to tamoxifen the rapy, and a short progression-free and overall survival after start of trea tment for recurrent disease. in Cox multivariate analyses for response to t herapy and for (progression-free) survival, corrected for age/menopausal st atus, disease-free interval, site of relapse and steroid hormone receptor s tatus, PSA was an independent variable of poor prognosis. It is concluded t hat the level of PSA in cytosols of primary breast tumours might be a marke r to select breast cancer patients who may benefit from systemic tamoxifen therapy.