What's new in tumor markers for prostate cancer?

The clinical features of a new prostate tumor marker, prostate-specific antigen (prostate antigen, PA), has been reviewed. Although PA cannot be used in early detection of prostate cancer, simultaneous determination of PA and PAP yields an additive clinical value in immuno-diagnosis of prostate cancer. At the present stage of development, PA is most useful as a prognostic marker for monitoring disease recurrence and treatment response. Also, PA is an effective immunohistologic marker for differential diagnosis of metastatic carcinomas with unknown primary, especially in the identification of metastatic prostate tumor in distant metastases and in the differentiation of primary prostate carcinoma from poorly differentiated transitional cell carcinoma of the bladder. Unequivocal evidence is not yet available on the role of circulating PA-binding globulin as an auto-antibody or an anti-tumor antibody as a result of patient's immune response. This observation is of clinical value for investigation of prostate cancer biology. The intriguing protease activity as detected in PA may provide new avenues for prostate cancer research.