Approximately 6% of women with newly diagnosed breast cancer will present with metastatic disease. Proper staging workup and diagnosis of metastatic lesions is crucial prior to surgical treatment.18F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is often included in the staging workup of locally advanced breast cancer. Recently, PET/CT with 18F-fluoroestradiol (18F-FES), a radiolabeled form of estradiol that binds to the estrogen receptor, has been approved as an additional imaging technique for the detection of estrogen receptor-positive lesions in patients with metastatic breast cancer. Though the two have been shown to have comparable sensitivity for diagnosis of metastatic lesions, there is still much debate regarding when to use 18F-FES PET/CT over 18F-FDG PET/CT imaging. We present the case of a 68-year-old patient diagnosed with estrogen and progesterone receptor-positive invasive ductal carcinoma of the left breast. Her staging workup included an 18F-FDG PET/CT that did not demonstrate any evidence of metastatic lesions. Due to discordant imaging findings, the patient then underwent 18F-FES PET/CT, which demonstrated over 90 metastatic osseous lesions. This study highlights the utility of 18F-FES PET/CT over 18F-FDG PET/CT in diagnosis of metastatic osseous lesions in a patient with metastatic estrogen receptor-positive breast cancer.
Keywords: 18F-fluoroestradiol; estrogen receptor–positive breast cancer; metastatic breast cancer; positron emission tomography/computed tomography.
18F-fluorodeoxyglucose PET/CT uses a glucose analogue preferentially taken up by malignant cells and is traditionally used in the staging workup of locally advanced or metastatic breast cancer.The use of 18F-fluoroestradiol PET/CT, which targets the estrogen receptor, was recently approved for evaluation of estrogen receptor–positive breast cancer. Its use may be considered in the staging workup in patients with estrogen receptor–positive tumors and discordant imaging findings on conventional imaging.
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