Prostatic cancer, acid phosphatase, creatine kinase-BB and race: a prospective study

To examine the effectiveness of prostatic acid phosphatase and creatine kinase-BB determinations in detecting prostatic cancer serum from 594 men more than 40 years was assayed for prostatic acid phosphatase with the thymolphthalein monophosphate substrate and a radioimmunoassay kit. Creatine kinase-BB levels also were measured with a radioimmunoassay kit. Patients with benign prostatic hyperplasia had higher prostatic acid phosphatase levels than normal controls. Accordingly, to avoid a high incidence of false positives in patients with benign prostatic hyperplasia the 92.5 percentile level of the patients with benign prostatic hyperplasia (3.9 ng./ml.) was chosen as the upper limit of normal. With this critical value elevated prostatic acid phosphatase levels were observed in 6 per cent of the patients with clinical stage A disease, 8 per cent with stage B, 35 pr cent with stage C and 68 per cent with stage D. The radioimmunoassay was no more effective than the enzymatic assay in detecting prostatic cancer. A correlation between prostatic acid phosphatase levels and patient race was observed, with 80 per cent of the black patients with extracapsular prostatic cancer having elevated prostatic acid phosphatase levels compared to 34 per cent of the white patients with similar stage disease. Creatine kinase-BB was elevated only in patients with advanced disease and was of little value in the diagnosis of prostatic cancer.