We have previously shown that serum prostate-specific antigen (PSA) is proportional to prostate cancer volume and that progression of prostate cancer is proportional to volume, but other investigators have not found serum PSA to be as useful in predicting pathologic stage at the time of radical prostatectomy. Because our series is the only study to examine prospectively all radical specimens at 3-mm intervals, we have examined the relationship between serum PSA and the morphologic indicators of cancer progression in our first 350 radical prostatectomies.

Preoperative serum PSA level was tabulated in 350 consecutive patients with prostate adenocarcinoma and compared with morphologic variables in the radical prostatectomy specimen. Morphologic variables included cancer volume, histologic grade, capsular penetration, seminal vesicle invasion, and lymph node metastasis.

Serum PSA showed strong correlation with all morphologic variables, which were highly intercorrelated. Serum PSA level was strongly correlated with cancer volume, histologic grade, and frequency of regional spread to lymph nodes. Close intercorrelations found between all variables were translated into a scale relating each level of serum PSA elevation to stage of disease in morphologic terms. Using this scale, serum PSA level can contribute to patient evaluation and treatment decisions in men with prostate cancer. Conclusions. Serum PSA is primarily determined by prostate cancer volume and secondarily by the percentage of high-grade cancer (Gleason grades 4 and 5) in the prostate. Because of this basic relationship, serum levels of PSA provide a clinically useful estimate of morphologic findings in the prostate. Serial PSA determinations should reflect the growth of the cancer as well as the gradual evolution of more malignant cells with the passage of time. The use of a serum PSA-based rating scale can contribute to patient evaluation and treatment decisions in men with prostate cancer.