A retrospective review of 102 consecutive patients with surgically staged, clinically localized prostatic carcinoma was performed to determine the relationship between pre-treatment enzymatic acid phosphatase values and histopathological extent of the tumor. Of 96 patients with normal pretreatment acid phosphatase titers (thymolphthalein monophosphate substrate) 77 (80 per cent) had values in the lower and 19 (20 per cent) had values in the upper half of the normal range. Of the latter 19 patients 16 (84 per cent) had histological evidence of extraprostatic tumor extension. Similarly, 5 of 6 patients (83 per cent) with elevated pre-treatment acid phosphatase titers had extraprostatic extension and 1 had a persistent postoperative acid phosphatase elevation that normalized with megestrol acetate therapy. Thus, 22 of 25 patients (88 per cent) with acid phosphatase values in or above the upper half of the normal range had either histological or clinical evidence of extracapsular tumor extension. By contrast, 41 of the 77 patients (53 per cent) with acid phosphatase titers in the lower half of the normal range had extracapsular extension. The predictive value for extraprostatic tumor extension of an acid phosphatase level in the upper half of the normal range was 84 per cent. Furthermore, in the 96 patients with normal acid phosphatase titers the incidence of extraprostatic tumor extension was significantly greater (p less than 0.01, chi-square) in those with values in the upper rather than the lower half of the normal range. Acid phosphatase titers in the upper half of the normal range were proportionately more common among patients with high grade and high clinical stage tumors. However, among patients with low grade and low stage tumors an acid phosphatase value in the upper half of the normal range was an independent variable that correlated with the presence of extracapsular tumor extension. These results confirm previously reported adverse prognostic implications of enzymatic acid phosphatase titers in or above the upper half of the normal range.
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