A Phase 2 Study of 16α-[18F]-fluoro-17β-estradiol Positron Emission Tomography (FES-PET) as a Marker of Hormone Sensitivity in Metastatic Breast Cancer (MBC)
16α-[18F]-fluoro-17β-estradiol positron emission tomography (FES-PET) quantifies estrogen receptor (ER) expression in tumors and may provide diagnostic benefit.
Women with newly diagnosed metastatic breast cancer (MBC) from an ER-positive primary tumor were imaged before starting endocrine therapy. FES uptake was evaluated qualitatively and quantitatively, and associated with response and with ER expression.
Nineteen patients underwent FES imaging. Fifteen had a biopsy of a metastasis and 15 were evaluable for response. Five patients had quantitatively low FES uptake, six had at least one site of qualitatively FES-negative disease. All patients with an ER-negative biopsy had both low uptake and at least one site of FES-negative disease. Of response-evaluable patients, 2/2 with low FES standard uptake value tumors had progressive disease within 6 months, as did 2/3 with qualitatively FES-negative tumors.
Low/absent FES uptake correlates with lack of ER expression. FES-positron emission tomography can help identify patients with endocrine resistant disease and safely measures ER in MBC.
Key wordsFES-PET FDG-PET Metastatic breast cancer ER expression Endocrine therapy Response
Acknowledgements and Support
The authors would like to thank Eunice How, the radiochemistry staff, nuclear medicine technologists, and physicists in the UW Department of Radiology as well as the staff of the Fred Hutchinson Breast Cancer Research Center Cancer Biology lab. This study was sponsored by the NCI Phase I and II Cancer Imaging Program (Contract #N01-CM-37008, Protocol 8052) and was supported by the UPCI Biostatistics Shared Resource (P30CA047904).
Conflict of interest
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