Prostate specific antigen and bone scan correlation in the staging and monitoring of patients with prostatic cancer.

The ability of serum prostate specific antigen (PSA) to predict bone metastases at initial presentation was determined in 146 patients, and in 66 patients during a 3-year period; 14.7% of patients with bone metastases at presentation had a PSA value less than 20 ng/ml. All patients who subsequently developed bone metastases had a PSA greater than 20 ng/ml and the rise in PSA often antedated the detection of bone metastases. Bone scans are still necessary in the initial staging but following diagnosis and treatment can be replaced by serum PSA measurement in monitoring patients with prostatic cancer.