FES-PET/CT (Cerianna) is an imaging tool for ER-positive metastatic breast cancer that uses a radiolabeled estradiol probe to visualize functional estrogen receptors. This helps confirm if tumors are truly ER-positive, unlike standard CT or FDG-PET scans.
It is particularly useful when lesions are hard to biopsy, when standard scans show unclear results, for detecting lobular breast cancer, predicting response to endocrine therapy, and spotting atypical metastases in bone marrow or brain.
Limitations include poor detection of liver metastases, interference from ER-binding drugs like Tamoxifen, and the fact that a negative scan doesn’t always mean absence of cancer. Future uses may include combining FES-PET with liquid biopsies or using it in early-stage breast cancer to guide therapy.