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Although multiple imaging modalities to evaluate treatment response in patients with metastatic breast cancer are used clinically, their comparative effectiveness has not been determined.
The purpose of this technical brief is to understand current utilization of metastatic breast imaging modalities for treatment evaluation in the United States, both in order to summarize the current state of the science and to inform future research on this topic.
We worked with Key Informants, including clinicians, patient advocates, representatives from the device manufacturing industry, and a product purchaser. Additionally, we searched gray and published literature from 2003 to 2013. We qualitatively synthesized the information from the Key Informant interviews and the gray literature. From the published literature, we abstracted data on the types of imaging used to evaluate treatment of metastatic breast cancer.
We identified bone scan (scintigraphy), magnetic resonance imaging (MRI), computed tomography (CT), and fluorodeoxyglucose-positron emission tomography (FDG-PET)/CT as the major modalities used for treatment evaluation of metastatic breast cancer in the United States. We also identified four types of imaging not commonly used currently that might become important within the next decade: F-fluoromisonidazole-(F-FMISO) PET/CT, fluorothymidine-(FLT) PET/CT, fluoroestradiol-(FES) PET/CT, and PET/MRI. All published reports pertaining to imaging evaluation of treatment response among metastatic breast cancer patients were limited to small observational studies. A review of the published literature found that, in general, uptake of tracers such as FDG in PET/CT scans is associated with tumor response as determined by bone scans, MRI, or CT.
Literature pertaining to imaging evaluation of treatment response among metastatic breast cancer patients was limited. An important potential advantage of FDG-PET/CT over conventional imaging for assessing tumor response among metastatic breast cancer patients is that it provides functional information regarding tumor metabolism in addition to information on gross morphologic changes. While some early evidence suggests that the metabolic response assessed by FDG-PET/CT after initial cycles of chemotherapy may be predictive of response to treatment among metastatic breast cancer patients, more rigorous research is needed before definitive conclusions can be reached. Future research efforts should focus on identifying novel radiotracers and biomarkers that may clarify breast tumor biology, addressing the lack of information on patient-centered outcomes (e.g., patient preferences) related to imaging, better delineating clinical outcomes associated with treatment response identified by imaging (e.g., progression-free and overall survival), and determining the costs associated with frequent imaging for treatment response.