Monoclonal prostate-specific antigen in untreated prostate cancer. Relationship to clinical stage and grade

The authors evaluated 440 men with clinically staged and untreated prostate cancer with a monoclonal prostate-specific antigen (PSA) assay. The serum PSA value correlated significantly with both the stage and grade of disease (P less than 0.00005). The relationships between PSA and consecutive Stages A, B, C, and D2 (alpha = 0.15) and between progressive Gleason's scores 2 to 4, 5 to 7, and 8 to 10 (alpha = 0.15) were statistically significant. Also statistically significant was the correlation between serum PSA level and intracapsular versus extracapsular disease (P less than 0.00005), although no one value can be used to differentiate reliably between patients in these two categories. The probability of clinically detectable metastasis (Stage D2) is 85% if the serum PSA level is greater than 30; however, 12% of patients without clinical evidence of metastases (Stages A, B, and C) have such a serum PSA value. Despite the statistically significant association between PSA and tumor differentiation and volume as reflected by tumor grade and clinical stage, this marker cannot be used to determine either for an individual patient.