Immunohistochemical labelling for prostate-specific antigen in breast carcinomas

Immunohistochemical detection of prostate-specific antigen (PSA) is an aid in determining the prostatic origin of metastatic cells. However, small amo unts of PSA have also been found in non-prostatic tissues and tumors, for e xample in some breast carcinomas, by highly sensitive immunofluorometric me thods, but also by immunohistochemistry. Our aim was to evaluate the preval ence and prognostic value of histologically confirmed PSA immunoreactivity in breast carcinoma. Sections of formalin-fixed, paraffin-embedded samples from 171 breast carci nomas were immunostained for PSA. The staining results were compared with t he mitotic activity, tumor size, histological grade, steroid receptors and follow-up data. For analysis the material was divided into subgroups accord ing to the patients' age (pre- and postmenopausal). PSA was found by immuno histochemistry in 54 (32) breast carcinomas. In survival analysis of the wh ole patient material PSA positivity did not show prognostic value. Among pr emenopausal patients concomitant estrogen receptor and PSA-negativity prove d to be associated with high risk of breast cancer death (RR 6.2), also aft er adjustment for tumor size, histological grade, and axillary lymph node s tatus. Among postmenopausal patients PSA positivity was associated with pro gesterone receptor positivity and high differentiation but not with age, no dal status, or mitotic activity. PSA can be detected by immunohistochemistr y in a considerable number of breast carcinomas. PSA immunoreactivity alone does not seem to have any value as general prognosticator of breast carcin oma patients. However, concomitant absence of PSA and estrogen receptors wa s an indicator of unfavourable prognosis among premenopausal patients.