[Prostatic specific antigen (PA) in mass screening for prostate cancer]

The usefulness of prostatic specific antigen (PA) was compared with that of prostatic acid phosphatase (PAP). PA was determined in the serum of 2,183 patient examined by the mass screening for prostate cancer from 1987 to 1990. The serum samples of these patients were obtained from our serum bank. PA was measured by the E test "TOSOH" II (PA). The relationship of PA and PAP to prostate size estimated by digital rectal examination (DRE) and ultrasound tomography (US), and age was investigated. PA and PAP correlated with aging and prostate size estimated by DRE. However PA was more apparently related with these things. The correlation between PA and prostatic size estimated by US was relatively high (r = 0.53), but the correlation between PAP and prostate size estimated by US was low (r = 0.20). When the upper limit of normal range was set at 6.0 ng/ml, the sensitivity, specificity and efficiency was 64%, 97% and 62%, respectively. PA was more sensitive than PAP and could be more useful since none of the patients with prostate cancer was PAP positive and PA negative. We conclude that PA should be a reliable tumor marker in our mass screening system.