Comparison of diagnostic sensitivity of [(18)F]fluoroestradiol and [(18)F]fluorodeoxyglucose positron emission tomography/computed tomography for breast cancer recurrence in patients with a history of estrogen receptor-positive primary breast cancer

BACKGROUND: To compare the diagnostic sensitivity of [(18)F]fluoroestradiol ([(18)F]FES) and [(18)F]fluorodeoxyglucose ([(18)F]FDG) positron emission tomography/computed tomography (PET/CT) for breast cancer recurrence in patients with estrogen receptor (ER)-positive primary breast cancer. METHODS: Our database of consecutive patients enrolled in a previous prospective cohort study to assess [(18)F]FES PET/CT was reviewed to identify eligible patients who had ER-positive primary breast cancer with suspected first recurrence at presentation and who underwent [(18)F]FDG PET/CT. The sensitivity of qualitative [(18)F]FES and [(18)F]FDG PET/CT interpretations was assessed, comparing them with histological diagnoses. RESULTS: Of the 46 enrolled patients, 45 were confirmed as having recurrent breast cancer, while one was diagnosed with chronic granulomatous inflammation. Forty (89%) patients were ER-positive, four (9%) were ER-negative, and one (2%) patient did not undergo an ER assay. The sensitivity of [(18)F]FES PET/CT was 71.1% (32/45, 95% CI, 55.7–83.6), while that of [(18)F]FDG PET/CT was 80.0% (36/45, 95% CI, 65.4–90.4) with a threshold of positive interpretation, and 93.3% (42/45, 95% CI, 81.7–98.6) when a threshold of equivocal was used. There was no significant difference in sensitivity between [(18)F]FES and [(18)F]FDG PET/CT (P = 0.48) with a threshold of positive [(18)F]FDG uptake, but the sensitivity of [(18)F]FDG was significantly higher than [(18)F]FES (P = 0.013) with a threshold of equivocal [(18)F]FDG uptake. One patient with a benign lesion showed negative [(18)F]FES but positive [(18)F]FDG uptake. CONCLUSIONS: The restaging of patients who had ER-positive primary breast cancer and present with recurrent disease may include [(18)F]FES PET/CT as an initial test when standard imaging studies are equivocal or suspicious.