F-18-Fluoroestradiol (Fes) And F-18-Fluorodeoxyglucose (Fdg) Pet Imaging In Lobular Breast Cancer.

1063Background: The histology and pattern of spread in lobular breast cancer has presented challenges in estimating extent of disease by traditional imaging methods. 18F-FES is an estrogen analogue PET imaging tracer which measures tumor ER expression at multiple tumor sites simultaneously. We compared quantitative FES-PET and clinical FDG-PET SUV uptake between patients with metastatic lobular and ductal carcinoma. Methods: We retrospectively compared FES and FDG SUV uptake between ER+ lobular and ductal metastatic breast cancer patients (199 ductal, 44 lobular) enrolled in various studies at our institution. Up to nine lesions in each patient were evaluated by FES SUVmax and/or FDG SUVmax for a total of 619 lesions in FES images (n = 509 ductal, n = 110 lobular) and 466 lesions in FDG images (n = 378 ductal, n = 88 lobular). Using linear mixed-effects models, we assessed differences between lobular and ductal histologies in both FES SUVmax and FDG SUVmax. Overall survival (OS), from time of FES-PET scan...