Bone scanning and plasma phosphatases in carcinoma of the prostate.

Bone scanning with 99mTc-Sn-HEDP, radiographic skeletal survey and determination of plasma acid and alkaline phosphatase values were carried out in a consecutive series of 90 untreated patients with carcinoma of the prostate. 99mTc-Sn-HEDP provided satisfactory bone imaging and was convenient in use. The addition of bone scanning to radiographic survey increases the detection rate of skeletal metatases by 16%. Radiography increases the accuracy of bone scanning by identifying false positive scans due to benign disease and false negative scans when there are diffuse symmetrical bony metastases. The plasma phosphatases alone are less accurate staging tests. The acid phosphatase data support the validity of scan positive--X-ray negative findings. Bone scan abnormalities due to secondary deposits usually precede elevation of plasma alkaline phosphatase.