PROSTATE-SPECIFIC ANTIGEN IN SERUM OF WOMEN WITH BREAST-CANCER

Prostate-specific antigen (PSA) was recently found in 30% of female br east tumours. In this study we have examined if PSA circulates in the blood of breast cancer patients and if serum PSA has any clinical appl ication. We have compared serum PSA levels between women with and with out breast cancer, between women with PSA-positive and PSA-negative br east cancer and between women with breast cancer before and after surg ical removal of the tumour. We found that for women greater than or eq ual to 50 years, there is no difference in serum PSA between normal or breast cancer patients. We also could not find any difference in pres urgical or post-surgical serum PSA between women who have PSA-positive or PSA-negative breast cancer. We found no correlation between PSA co ncentrations in matched presurgical and post-surgical sera, between pr esurgical sera and tumour cytosols and between post-surgical sera and tumour cytosols. High-performance liquid chromatography has shown that PSA in normal male serum consists mostly of PSA bound to alpha(1)-ant ichymotrypsin (molecular weight approximately 100 000), and PSA in bre ast tumours and presurgical and post-surgical serum consists mostly of free PSA (molecular weight approximately 33 000). These data suggest that female serum PSA is not associated with tumour PSA levels. We spe culate that most of the circulating PSA in women originates from the n ormal breast. It appears that serum PSA in women does not have potenti al for breast cancer diagnosis or monitoring, but our previous data ar e consistent with the view that tumour PSA concentration is a favourab le prognostic indicator in women with breast cancer.