The effect of drug therapy on the uptake of radioactive fluorine by osseous metastases

RadioisotopiC techniques are potentially of considerable value to clinical pharmacology. Scintigrams and uptake studies are of particular interest, as they permit one to visualize lesions in many organs and to obtain simultaneously quantitative information on the degree of abnormality in the area of the lesion. Bone metastases take up increased amounts of fluorine‐18; the present study was an investigation of the effect of therapy on this abnormal uptake. In eight patients with metastatic lesions to bone, chemotherapy or hormonal therapy produced temporary improvement in five, as ;udged by roentgenographic or clinical criteria, during the first four months after initiation of therapy. Serial scintigrams and quantitative uptake studies throughout this period showed that the abnormal ratio in fluorine uptake remained unchanged, despite the other evidence of emporary regression of metastases. Although the duration of time chosen for this study was consistent with that commonly used by physicians for evaluation of the effect of a given type of chemotherapy, our results suggest that such short‐term studies must be interpreted cautiously.