Significance of Increased Phosphatase Activi1'¥ of Bone at the Site of Osteoplastic Metastases Secondary to Carcinoma of the Prostate Gland

Recent determinations of serum phosphatase activity in patients with cancer (1, 2, 3) suggest that values obtained in cases with widespread osteoplastic metastases are, in general, significantly higher than those found in association with osteolytic metastases. In the series reported by Gutman, Tyson and Gutman (1), for example, the serum phosphatase activity exceeded 10 Bodansky units per 100 c.c. in 6 of 10 cases with osteoplastic metastases but in only 3 of 19 patients with osteolytic metastases. In 2 patients with very extensive osteoplastic skeletal lesions, values exceeding 100 Bodansky units per 100 C.c. of serum were obtained, as contrasted with the normal maximum of 4.0 Bodansky units. It has been assumed (1, 3) that the rise in phosphatase activity of the serum in such cases is the result of increased elaboration of phosphatase, which is subsequently released into the circulating fluids. Direct evidence in support of this assumption is afforded by the present investigation, which disclosed strikingly increased phosphatase activity of bone at the site of osteoplastic skeletal metastases in a patient with carcinoma of the prostate gland. This observation is of interest also because it is in accord with the view, derived from pathological studies, that the mechanism of bone formation in metastatic osteoplastic neoplasms is fundamentally the same as that of normal bone formation. Of particular interest is the further implication that the capacity to stimulate production of phosphatase may play an important rOle in determining the osteoplastic character of the metastatic bone lesions observed in association with certain neoplasms. In this respect, too, chemical studies tend to support the views of pathologists who have long postulated the elaboration by certain tumor cells of a chemical factor initiating bone formation in osteoplastic metastases.