Objectives: Nearly half of men with clinically localized prostate cancer are understaged. We evaluated whether knowledge of preoperative free prostate-specific antigen (f-PSA), complexed (c-PSA), and total (t-PSA) concentrations or the ratios thereof (f-PSA/t-PSA, c-PSA/t-PSA, and f-PSA/c-PSA) could improve upon the staging of prostate cancer when compared with standard PSA testing (t-PSA). In addition, we examined their associations with tumor grade and deoxyribonucleic acid (DNA) ploidy.
Methods: Two hundred ninety patients with prostate cancer, 178 (61%) of whom were treated with radical prostatectomy, formed the study group.
Results: Although there were significant differences in the f-PSA concentrations with respect to clinical stage, considerable overlap in PSA levels among the clinical substages was observed. Statistically significant differences but weak correlations were observed between the individual f-PSA, c-PSA, and t-PSA concentrations with regard to pathologic stage (organ-confined versus extraprostatic) and grade. No significant relationship, however, was observed with the three ratios. Higher PSA values were not always associated with a pathologic stage of pT3 or greater, and lower levels did not ensure that a tumor was organ-confined. Only a slight association was observed between c-PSA and t-PSA levels and DNA ploidy. No significant relationship was observed between the f-PSA levels as well as the three ratios with regard to DNA ploidy. A statistically significant improvement in predicting pathologic stage was observed when combining knowledge of preoperative t-PSA concentration with the c-PSA/t-PSA ratio. However, the area under the receiver operator characteristic curves was only slightly increased; as such this combination was of limited clinical utility.
Conclusions: Statistically significant but weak correlations were observed between the molecular forms of PSA and stage, grade, and DNA ploidy. The significant overlap in f-PSA and c-PSA values among all stages, grades, and ploidy values precluded any useful predictive information for the individual patient. As such, preoperative knowledge of f-PSA and c-PSA values and the three ratios provided no additional diagnostic information over standard PSA (t-PSA) values alone.