Rationale and objectives: The authors performed this study to determine the feasibility of using quantitative 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) to monitor the response of breast cancer bone metastases to therapy.
Materials and methods: Twenty-four women with stage IV bone-dominant breast carcinoma were included in this study. Whole-body FDG PET imaging was performed at serial time points during the course of therapy. FDG PET scans were interpreted quantitatively by using the maximum standard uptake value (SUV) of the most conspicuous bone lesion at baseline FDG PET. PET results were compared to the overall assessment of response (response, stable disease, progressive disease) with a combination of conventional imaging, change in tumor marker values, and subjective symptom changes by experienced medical oncologists blinded to the findings at FDG PET. Changes in FDG SUV were also correlated quantitatively to the changes in a particular tumor marker (CA 27.29).
Results: The changes in FDG SUV with therapy showed correlation with the overall clinical assessment of response (P < .01). The percentage change in FDG uptake with therapy showed strong correlation with the percentage change in tumor marker value (P < .01).
Conclusion: Preliminary results indicate that serial whole-body FDG PET can help quantitatively assess the response of breast cancer bone metastases to therapy. Prospective trials are needed to further investigate its accuracy.