N 1953 Fishniari arid Lernera suggested that I the inhibitory action of L-tartrate on acid phosphatase, which had been described by Abul-Fad1 and King, might be applied in the differentiation between the serum acid phosphatase of nonprostatic origin and that coming from the prostate. They devised a method that involved the determination of serumacid-phosphatase activity in the presence and in the absence of 0.02 A4 L-tartrate. T h e difference between these two values represented the acid phosphatase of prostatic origin. Moreover, Fishman and his co-workers5 proposed the thesis that the tartrate-inhibited, or prostatic, fraction of serum acid phosphatase might be increased in carcinoma of the prostate, either localized or metastatic, when the serum acid phosphatase determined in the usual manner, that is, the total serum acid phosphatase, was normal. They found that four out of five patients with proved prostatic cancer but without evidence of metastases and with normal total serum-acid-phosphatase values had elevated values for the prostatic serum-phosphatase portion.
The first part of the present investigation consisted in determining whether any elevations in the prostatic fraction of serum acid phosphatase could be uncovered among men coming to a cancer-prevention clinic for general examination who did not have any symptoms of prostatic carcinoma. T h e second part of the study concerned itself with following patients who showed such elevations to determine whether these elevations represented a forerunner of prostatic cancer and whether, in the course of time, clinical evidence of this