Head-to-head comparison of F-FDG and F-FES PET/CT for initial staging of ER-positive breast cancer patients.

Purpose: To compare the diagnostic performance of F-fluorodeoxyglucose (F-FDG) and F-fluoroestradiol (F-FES) positron emission tomography/computed tomography (PET/CT) for initial staging of estrogen receptor (ER) positive breast cancer.

Methods: Twenty-eight patients with ER-positive breast cancer underwent F-FDG and F-FES PET/CT for initial staging. Diagnostic performance and concordance rates were analyzed for both radiotracers. Semiquantitative parameters of maximum standardized uptake value (SUVmax) and tumor-to-normal ratio (T/N ratio) were compared using Wilcoxon signed-rank test. Factors potentially affecting the degree of radiotracer uptake were analyzed by multi-level linear regression analysis.

Results: The overall diagnostic performance of F-FES was comparable to F-FDG, except for higher specificity and NPV, with sensitivity, specificity, PPV, NPV, and accuracy of 87.56%, 100%, 100%, 35.14%, and 88.35%, respectively, for F-FES and 83.94%, 30.77%, 94.74%, 11.43%, and 95.37%, respectively, for F-FDG. Diagnostic performance of strong ER expression was better in F-FES but worse for F-FDG. There was a correlation of mucinous cell type and Allred score 7-8 with F-FES uptake, with correlation coefficients of 26.65 (19.28, 34.02), 5.90 (- 0.005, 11.81), and p-value of < 0.001, 0.05, respectively. Meanwhile, luminal B and Ki-67 were related to F-FDG uptake, with correlation coefficients of 2.76 (1.10, 0.20), 0.11 (0.01, 0.2), and p-value of 0.018, 0.025, respectively.

Conclusion: Diagnostic performance of F-FES is comparable to F-FDG, but better for strongly ER-positive breast cancer. Combination of F-FES and F-FDG would potentially overcome the limitations of each tracer with more accurate staging.