Screening for carcinoma of the prostate. Rectal examination, and enzymatic and radioimmunologic measurements of serum acid phosphatase compared.

Veterans (n = 771, 54-76 years of age) from the Second World War, who attended a rehabilitation program arranged by the state between the years 1979 and 1983, were screened for prostatic cancer by rectal examination of the prostate and by measurement of serum prostate-specific acid phosphatase (PAP) concentration and enzyme activity (total and tartrate-labile). Nine cases with prostatic cancer confirmed by needle biopsy were found. Serum PAP concentrations were elevated in five of the nine cancer patients and rectal examination was positive in six of them, whereas the serum PAP concentration was elevated and rectal examination was positive simultaneously only in two patients. Serum PAP concentrations were elevated in 25 patients without prostatic cancer, and rectal palpation of the prostate resulted in 21 false-positive findings. The enzyme activity of serum acid phosphatase was not elevated in any of the nine patients diagnosed as having prostatic cancer. The predictive value of a positive finding in serum PAP concentration (16.7%) or rectal palpation of the prostate (22.2%) in this unselected, asymptomatic population was similar and low. Both tests together gave additive information.