Prostate-specific antigen ratio correlates with aggressiveness of histology grades of prostate cancer

Abstract

Objectives: To compare prostate-specific antigen (PSA) ratio to total PSA (tPSA) assay for prostate cancer diagnosis and to study the correlation of PSA ratio with histology grade of prostate cancer. Methods: Among 334 selected cases, 136 had benign prostate diseases and 198 had prostate cancer. All cases underwent transrectal ultrasound (TRUS) and tissue biopsies within 6 months of their tPSA measurements. All of the tPSA levels taken were between 2 and 20 μg/L. The serum tPSA and free PSA were assayed using the Abbott AxSYM immunoassay system (Abbott Laboratories; Abbott Park, IL, USA). The PSA ratios of patients with prostate cancer were compared to those with benign prostate diseases (BPD) using the Student’s t test. Correlation between the histology grades and PSA ratios was calculated by Pearson test. Receiver operating characteristic (ROC) curves were generated from sensitivities and specificity of various PSA ratios and tPSA levels. Results: We found an inverse correlation between PSA ratios and aggressiveness of histology grades ( r = −0.995, p < 0.01). The higher the histology grade, the lower the PSA ratio tended to be, and the more sensitive and specific the PSA ratio was in the diagnosis of prostate cancer. No correlation was found between histology grades and tPSA levels. A PSA ratio of 0.25 diagnosed 93% of patients with Gleason score greater than 7 and 83% of all prostate cancer patients. It would have reduced unnecessary biopsies by 23% compared to the tPSA level of 4 μg/L. Sensitivity of PSA ratios was higher and specificity was lower in high tPSA level group than they were in low tPSA level group. Conclusions: PSA ratio inversely correlates to aggressiveness of prostate cancer and has a potential to predict histology grade of prostate cancer. PSA ratio improves sensitivity and specificity for prostate cancer diagnosis compared to tPSA assay.