Tumour markers in prostatic cancer

Abstract

Prostate cancer is now the third commonest cancer in men. Extensive clinical trials comparing acid phosphatase, alkaline phosphatase (ALKP) and prostate specific antigen (PSA) have shown that PSA is the most sensitive and specific of the tumour markers available for prostate cancer. Caution is needed when comparing the results from different assay methods, there is no international standard for PSA. In the management of localised disease, radical treatment can reduce the PSA levels to less than 0.4 ng/ml, similar results can be obtained for a varying duration in patients sensitive to androgen withdrawal. Raised levels greater than 0.4 ng/ml after radical prostatectomy are indicative of residual disease. PSA is valuable in monitoring deferred treatment or the effects of hormone manipulation and give an indication of the prognosis and early warning of recurrence. In extensive metastatic disease the combination of PSA and ALP reflects the tumour activity. Less than 15 hot spots on the scintigram at presentation and a PSA less than 10 ng/ml 3 to 6 months after commencing treatment is associated with prolonged survival. The role of PSA in population screening for early prostatic cancer is uncertain; early results suggest it can be used in combination with digital rectal examination and ultrasonic examination of the prostate. The effect of a PSA decision level at 4 or 10 ng/ml has a considerable influence on the pick up rate.