Real-world application of ¹⁸F-FES PET/CT on HR + breast cancer patients with brain metastases

¹⁸F-fluoroestradiol positron emission tomography/computed tomography (¹⁸F-FES PET/CT) offers a novel method for assessing whole-body estrogen receptor (ER) expression in metastatic breast cancer. Brain metastases significantly impact survival in hormone receptor positive (HR +) patients, yet the role of FES-PET in this setting remains underexplored.

We retrospectively screened 1049 patients who underwent ¹⁸F-FES PET/CT from 2012 to 2024 at Fudan University Shanghai Cancer Center. Of these, 23 HR + breast cancer patients with intracranial lesions were included and followed for a median of 21.5 months. Survival outcomes, including intracranial progression-free survival (PFS), were analyzed, and FES-related parameters measured and verified.

Among the 23 patients, 7 (30.4%) developed intracranial symptoms, 12 (52.2%) received radiotherapy or surgery, and 16 (69.6%) received endocrine-based systemic therapy. FES-PET showed 80% concordance with MRI and 100% with pathology. Patients with the high maximum standardized uptake value (SUVmax) (≥ 1.8) demonstrated a markedly prolonged intracranial PFS compared to those with lower values (mPFS not reached vs 3.75 months, p < 0.001). ROC curve analysis established FES SUVmax as a significant predictor of intracranial progression (AUC = 0.742; 95% CI, 0.556-0.928). Multivariate analysis further identified FES SUVmax classification (HR = 7.985, 95% CI 1.214-52.506, p = 0.031) and disease-free interval (DFI) (HR = 0.033, 95% CI 0.005-0.211, p < 0.001) as the significant, independent predictors of intracranial PFS.

Our results confirm the vital role of ¹⁸F-FES PET/CT as evaluation method and predictive tool for assessing intracranial disease in HR + breast cancer patients, highlighting its capacity to potentially improve personalized treatment strategies.