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.