Correlation between bone scans and serum levels of osteocalcin, prostate-specific antigen, and prostatic acid phosphatase in monitoring patients with disseminated cancer of the prostate.

Response of prostatic cancer bone metastases to therapy (androgen withdrawal and Estracyt) was studied in 43 patients by applying scintiscanning and radioimmunodetective measurement of serum osteocalcin (OC) values. The prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP) concentrations, as sensitive probes for the overall tumor spread, were used in parallel in a monitoring procedure. A significant rise in OC levels to values elevated from a pretreatment normal level has been found in patients with a partial osseous tumor remission, and this may be easily distinguished from normal and/or subnormal OC level in bony tumor progression (P less than 0.01) and during stabilization in metastatic spread (P less than 0.01). On these bases, differences between disease progression and the "no change" response category could not be statistically recognized (P greater than 0.05). A sharp increase in circulating OC level has been recorded 1 months after the beginning of the treatment leading to bone remodeling processes and precedes improvements in scintiscan appearance. Blood OC concentration seems also to be of utility 1) in distinguishing scintigraphic flare phenomenon from a slight bone scan progression and 2) when related to scans with regions of both disease improvement and worsening. Furthermore, serum OC concentration can frequently be measured through a noninvasive procedure, thus serving as a significant addition to bone scintigraphy.