Alpha1-antichymotrypsin-PSA (ACT-PSA):: A useful marker in the differential diagnosis of benign hyperplasia and cancer of the prostate?

This study examined the clinical relevance of the determination of alpha(1)-antichymotrypsin complexed PSA (ACT-PSA) in addition to fetal PSA antigen (t-PSA). Patients and Methods: Both total PSA-and ACT-PSA-values of frozen sera obtained pretherapeutically from 93 patients with carcinoma (PC) and 132 patients with benign hyperplasia of the prostate (BPH) were analyzed by means of PSA sandwich-ELISA (Dianova GmbH) and ACT-PSA sandwich-ELISA (Dianova GmbH). Results: At 95% specificity (true negative test results), a cutoff value of 18.9 [mu g/L] was obtained for total PSA (7 patients with BPH [5%] were above this value). For this cutoff value we calculated a sensitivity (hue positive test results) of 41%. Using the same criteria for the ratio Q = ACT-PSA: t-PSA (percentage of ACT-PSA) a cutoff of 6.0 was found again at a specificity of 95%. In a second step only patients with total PSA values below the cutoff level of 18.9 [mu g/L]) were considered. Out of these patients 119 of 125 with BPH and 3 of 54 with PC were below the above mentioned ratio ((Q=6.0). Considering both steps (total PSA and Q) 42 patients with PC were detected correctly and 15 patients with BPH would have been biopsied unnecessarily. Conclusion. High total PSA levels are a very good indicator for the presence of prostate cancer. There is still concern to improve the differentiation of the diagnosis between BPH and PC, when an intermediate or low value (less than or equal to 95% specificity) is observed. The determination of Q=ACT=PSA: t-PSA is not to be recommended because it might not be helpful for the clinicians decision to perform biopsy.