title: Quantitative fluoroestradiol positron emission tomography imaging predicts response to endocrine treatment in breast cancer.
abstract: OBJECTIVE
  In breast cancer, [(18)F]fluoroestradiol (FES) positron emission tomography (PET) correlates with estrogen receptors (ER) expression and predicts response to tamoxifen. We tested the ability of FES-PET imaging to predict response to salvage hormonal treatment in heavily pretreated metastatic breast cancer patients, predominantly treated with aromatase inhibitors.
  
  
  METHODS
  Initial FES uptake measurements in 47 patients with ER-positive tumors were correlated with subsequent tumor response to 6 months of hormonal treatment. Most patients had bone dominant disease and prior tamoxifen exposure. Response was compared to initial FES-PET uptake, measured qualitatively and quantitatively using standardized uptake value (SUV) and estradiol-binding flux.
  
  
  RESULTS
  Eleven of 47 patients (23%) had an objective response. While no patients with absent FES uptake had a response to treatment, the association between qualitative FES-PET results and response was not significant (P = .14). However, quantitative FES uptake and response were significantly associated; zero of 15 patients with initial SUV less than 1.5 responded to hormonal therapy, compared with 11 of 32 patients (34%) with SUV higher than 1.5 (P < .01). In the subset of patients whose tumors did not overexpress HER2/neu, 11 of 24 patients (46%) with SUV higher than 1.5 responded.
  
  
  CONCLUSIONS
  Quantitative FES-PET can predict response to hormonal therapy and may help guide treatment selection. Treatment selection using quantitative FES-PET in our patient series would have increased the rate of response from 23% to 34% overall, and from 29% to 46% in the subset of patients lacking HER2/neu overexpression. A multi-institutional collaborative trial would permit definitive assessment of the value of FES-PET for therapeutic decision making.
authors: Division of Medical Oncology, University of Washington, Seattle Cancer Care Alliance, Seattle, WA 98109, USA. hmlinden@u.washington.edu
authors: Hannah M
authors: HM
authors: Linden
authors: Svetlana A
authors: SA
authors: Stekhova
authors: Jeanne M
authors: JM
authors: Link
authors: Julie R
authors: JR
authors: Gralow
authors: Robert B
authors: RB
authors: Livingston
authors: Georgiana K
authors: GK
authors: Ellis
authors: Philip H
authors: PH
authors: Petra
authors: Lanell M
authors: LM
authors: Peterson
authors: Erin K
authors: EK
authors: Schubert
authors: Lisa K
authors: LK
authors: Dunnwald
authors: Kenneth A
authors: KA
authors: Krohn
authors: David A
authors: DA
authors: Mankoff