DETECTION OF BONE METASTASES IN BREAST-CANCER BY (18)FDG PET - DIFFERING METABOLIC-ACTIVITY IN OSTEOBLASTIC AND OSTEOLYTIC LESIONS

Purpose: (99m)Technetium methylene diphosphonate (Tc-99m MDP) bone sci ntigraphy is currently the method of choice for the detection of bone metastases, but F-18-fluoro-deoxy-D-glucose positron emission tomograp hy ((18)FDG PET) offers superior spatial resolution and improved sensi tivity. We have compared (18)FDG PET with Tc-99m MDP bone scintigraphy in patients with skeletal metastases from breast cancer and have anal yzed the data in subgroups based on radiographic characteristics of le sions. Patients and Methods: Twenty-three women with breast cancer and confirmed bone metastases were studied with both 99mTc MDP bone scint igraphy and (18)FDG PET, and the number of lesions detected and the qu antitation of uptake (standardised uptake values [SUVs]) of (18)FDG in osteolytic and osteoblastic metastases were compared. Survival was co mpared for both lytic and blastic bone metastases and for patients wit h high and low accumulation of (18)FDG. Results: (18)FDG PET detected more lesions than Tc-99m MDP scintigraphy (mean, 14.1 and 7.8 lesions, respectively; P < .01). However, (18)FDG detected fewer bone metastas es compared with 99mTc MDP scintigraphy in a subgroup of patients with osteoblastic disease (P < .05). Higher SUVs were observed for osteoly tic than osteoblastic disease (mean, 6.77 and 0.95, respectively; P < .01). Survival was lower in patients with osteolytic disease compared with the remainder (P = .01). A difference in survival was not found f or those patients with high SUVs (> 3.6; P = .4). Conclusion: (18)FDG PET is superior to bone scintigraphy in the detection of osteolytic br east cancer metastases, which led to a poorer prognosis. In contrast, osteoblastic metastases show lower metabolic activity and are frequent ly undetectable by PET. The biologic explanation for this observation remains ta be elucidated. (C) 1998 by American Society of Clinical Onc ology.