The value of serum enzymatic acid phosphatase in the staging of localized prostate cancer

With the development of reliable assays for the measurement of prostate specific antigen (PSA), the use of serum enzymatic acid phosphatase in the staging of disease before radical prostatectomy has been called into question. We evaluated 460 consecutive men who were referred to our institution as candidates for radical prostatectomy. Staging evaluation included digital rectal examination, serum measurements of enzymatic acid phosphatase and PSA, bone scans and, in patients in whom advanced clinical stage was anticipated, computerized tomography, magnetic resonance imaging or transrectal ultrasonography. Of the 460 men 21 (4.6%) had elevations of serum enzymatic acid phosphatase. All 19 men with elevations who were fully evaluated proved to have either positive bone scans, extraprostatic extension of disease, PSA greater than 100 ng./ml., positive lymph nodes or positive seminal vesicles. However, in 17 of the 21 men (81%) with elevated serum enzymatic acid phosphatase advanced disease was detected by either abnormal digital rectal examination or PSA alone. Thus, serum enzymatic acid phosphatase provided unique information in only 4 of the entire study population (0.9%). Recognizing this low yield of unique information, we believe that measurements of serum enzymatic acid phosphatase are no longer mandatory before radical prostatectomy but may provide important confirmatory information in patients in whom advanced disease is suspected.