[Factors affecting the PSA:alpha 1 antichymotrypsin/total PSA ratio]

To evaluate the influence of several factors, including age, prostate volume, total PSA (PSA-T), clinical stage and Gleason on the PSA:alpha 1ACT/PSA-T (C/T) ratio.

Using in-house assays, we measured plasma levels of PSA-T and PSA:alpha 1ACT complex in 622 patients with benign prostate hyperplasia (BPH) (455 with hystological confirmation and 167 with clinical evidence of absence of malignance) and in 255 patients with prostate cancer (CaP), and determined the correlation between different parameters.

In BPH patients, PSA-T and PSA:alpha 1ACT significantly increased with age. There was a positive correlation between age and PSA-T (r = 0.161, p < 0.0001) and PSA:alpha 1ACT (r = 0.141, p = 0.001). In contrast, the C/T ratio remained constant and below 70% in all decades. Similar results were obtained in CaP patients. In BPH patients, there was a positive correlation between prostate volume and PSA-T and PSA:alpha 1ACT, but not with the C/T ratio. In CaP patients, however, there was a negative correlation between prostate volume and the C/T ratio. An excellent correlation was found between PSA-T and PSA:alpha 1ACT, and a good correlation between PSA-T and the C/T ratio and between PSA:alpha 1ACT and C/T ratio. A multiple regression analysis showed that, in HBP and CaP patients, PSA-T and PSA:alpha 1ACT complex were the only parameters that significantly and independently influenced the C/T ratio.

The C/T ratio is independent of age, prostate volume, Gleason and clinical stage. Therefore, these factors need not to be considered when using the C/T ratio.