Molecular forms of prostate-specific antigen and human kallikrein 2 as promising tools for early diagnosis of prostate cancer

Prostate-specific antigen (PSA) is the most useful marker in the early dete ction of prostate cancer and for the monitoring of patients with this diagn osis. Molecular forms of PSA and also human kallikrein 2 have been used to discriminate between benign prostatic hyperplasia and prostate cancer as we ll as for the detection of prostate cancer within the gray zone of PSA, In this respect, a literature survey on the diagnostic validity of free PSA (f PSA) related to total PSA (tPSA), PSA bound to alpha (1)-antichymotrypsin ( ACT-PSA), and complexed PSA is given together with our results. The ratio o f fPSA:tPSA has been shown to improve the specificity of prostate cancer di agnosis on the basis of tPSA measurements. Unnecessary biopsies can be redu ced by about 19-64% in the total PSA range of 4-10 mug/liter while only mis sing 5-10% of cancers. Furthermore, carcinomas in patients with PSA values <4 <mu>g/liter can be detected, indicating an improved sensitivity because of the percent fPSA at low PSA values. ACT-PSA or complexed PSA alone and t he calculated derivatives are not superior in their discriminatory power co mpared with the percent fPSA, The diagnostic significance of the other mole cular PSA forms and human kallikrein 2 needs to be evaluated in more extens ive clinical trials.