35'th Annual Congress of Nuclear Medicine, Barcelona, İspanya, 15 - 19 Ekim 2022
The Contribution of 18 F-FES PET/CT in Therapy Management of Estrogen Receptor Positive Breast
Cancer
Purpose: We investigated the contribution of 18 F-FES PET/CT in therapy management of estrogen
receptor positive (ER+) breast cancer.
Methods: Pre-treatment prospective 18 F-FES PET/CT scans were planned to the patients who
performed 18 F-FDG PET/CT for ER+ breast cancer (ER: >10%). The histopathology, MRI-US, PET/CT
findings and follow-up data of the patients were documented. PET/CT findings were interpreted with
the knowledge of clinical and histopathological findings. Suspicious lesions were verified by further
imaging or biopsy. The contribution of 18 F-FES PET/CT on therapy management was evaluated
through pre and post 18 F-FES PET/CT questionnaire forms filled by clinicians. Management changes
were categorized as inter or intramodality change based on 18 F-FES PET/CT findings.
Results: 14 female patients who underwent 18 F-FDG and 18 F-FES PET/CT for staging (n: 12) or
restaging (n: 2) of ER+ breast cancer were included to study (mean age: 54). Based on breast
MRI-US and 18 F-FDG PET/CT findings, early stage, locally advanced and metastatic disease were
determined in 3(21,4 %), 6(35,7 %), and 5(35,7 %) patients, respectively. In 2 of them, multiple
metastases (n:>20) were detected by both PET/CT modalities. In the remaining 12 patients, 18 F -FDG
PET/CT defined 35 FDG positive metastases, while 18 F-FES PET/CT defined 33 ER+ metastases. The
median SUVmax of primary tumor in 18 F-FDG and 18 F-FES PET/CT was 4,65 (1,5 - 10,9) and 2,76 (0,98-
8,63); of axillary lymph node metastases 3,36 (2,7 - 15,7) and 2,69 (1,2 - 13,88); of non-axillary
metastases 3,31 (1,72-13,56) and 5,01 (0,93-14,68), respectively. 18 F-FES PET/CT findings downstaged
4 patients (28.5%), and therapy management was changed in 5 patients (35, 7%). Intermodality
change was occurred in 4 patients; 2 of them were operated initially and 2 patients were operated
after neoadjuvant chemotherapy instead of receiving adjuvant chemotherapy. Intramodality change
was occurred in one patient; radiotherapy area increased after 18 F-FES PET/CT.
Conclusion: 18 F-FES PET/CT contributed the therapy management of ER (+) breast cancer by
increasing accuracy combining with 18 F-FDG PET/CT in selected cases.
Key words: 18 F-FES PET/CT , 18 F -FDG PET/CT, Estrogen receptor, breast cancer