Significance of prostate-specific antigen-alpha(1)-antichymotrypsin complex for diagnosis and staging of prostate cancer

Objective: To evaluate the clinical significance of measuring the prostate- specific antigen-alpha (1)-antichymotrypsin (PSA-ACT) for differentiating p rostate cancer from benign prostate hypertrophy (BPH) and for the staging o f prostate cancer. Methods: Before treatment, total PSA (tPSA) and PSA-ACT were measured in 12 0 patients with prostate cancer and in 150 patients with BPH using immunofl uorometric techniques with different monoclonal antibodies against PSA and ACT. Furthermore, the tPSA and PSA-ACT densities of the whole prostate (PSA D and ACTD, respectively) were calculated. Results: tPSA, PSAD, PSA-ACT and ACTD levels in patients with prostate canc er paralleled the clinical stage and were significantly higher than those i n patients with BPH. Furthermore, these four values were significantly high er in patients with pathologically extraprostatic disease than those with o rgan-confined disease. Receiver operating characteristics analysis among pa tients with PSA values of 4.1-10 ng/ml revealed that the areas under the cu rve for tPSA and ACTD were similar to those for PSA-ACT and ACTD, respectiv ely and that no significant differences in the differentiation between pros tate cancer and BPH were observed among these parameters. Conclusions: Measurement of PSA-ACT provides useful information for the cli nical staging of prostate cancer and differential diagnosis between prostat e cancer and BPH; however, compared with tPSA, PSA-ACT may not be significa ntly superior in the diagnosis and staging of prostate cancer.