THE SIGNIFICANCE OF SERUM ALKALINE-PHOSPHATASE BONE ISOENZYME IN PROSTATIC-CARCINOMA WITH BONY METASTASIS

Objective To evaluate the clinical significance of serum alkaline phos phatase (ALP), ALP bone isoenzyme (ALPb) and prostate specific antigen (PSA) levels in predicting bony metastasis in prostatic carcinoma. Pa tients and methods The levels of serum ALP, ALPb and PSA were assessed in 32 patients with prostatic carcinoma and bony metastasis (group 1) , 31 with prostatic carcinoma without bony metastasis (group 2), and 3 1 with benign prostatic hyperplasia (group 3). Bony metastases were de tected using whole-body bone scintigraphy and ALPb was estimated elect rophoretically before surgical or medical treatment. The levels of the three markers were compared for their ability to predict bony metasta sis. Results In groups 1, 2 and 3, respectively, the mean (so) serum l evels of ALP were 304 (322.2), 76.6 (47.5) and 63.8 (14.7) IU/L, of AL Pb were 79.9 (76.9), 23.6 (9.9) and 25.3 (9.0) IU/L and of PSA were 47 8.1 (352.2), 46.9 (32.1) and 8.1 (1.8) ng/mL, The differences in serum ALP and ALPb between groups 1 and 2, and between groups 1 and 3 were significant (P < 0.05), but not those between groups 2 and 3. The posi tive predictive value (PPV) for bony metastasis in patients with prost atic carcinoma was 91.3% (21/23) and 100% (18/18) and the negative pre dictive value (NPV) was 71.8% (28/39) and 68.9% (31/45) for ALP and AL Pb, respectively. Conclusion Both serum ALP and ALPb were increased si gnificantly in patients with prostatic carcinoma with bony metastasis, The level of ALPb had a higher PPV and specificity for bony metastasi s than had the level of ALP, but a lower NPV and sensitivity than ALP or PSA (at PSA levels > 20 ng/mL).