title: In vivo prediction of response to antiestrogen treatment in estrogen receptor-positive breast cancer.
abstract: In metastatic breast cancer, the estrogen receptor (ER) is a well-known prognostic factor predictive of response to hormonal treatment in most, but not all, patients. Recently, a receptor-specific radioligand for in vivo imaging of the ER in breast cancer patients was developed: (123)I-labeled cis-11beta-methoxy-17alpha-iodovinyl-estradiol (Z-(123)I-MIVE). It showed high sensitivity and specificity for the in vivo detection of ER-positive breast cancer. The aim of this study was to determine whether Z-(123)I-MIVE scintigraphy is able to predict response or resistance to antiestrogen therapy in patients with metastatic ER-positive breast carcinoma.
  
  
  METHODS
  Twenty-three patients with first metastases of their breast cancer and positive Z-(123)I-MIVE scintigraphy were included and treated with tamoxifen, 40 mg/d. Scintigraphy was repeated, on average, 4 wk later. The results of these scintigraphies were compared with the clinical outcome.
  
  
  RESULTS
  On baseline scintigraphy, 21 of 23 patients had clear uptake and 2 of 23 patients had faint uptake of Z-(123)I-MIVE. After initiation of antiestrogen treatment, 17 of 21 patients with clear uptake on baseline scintigraphy showed complete blockade of ER activity on the Z-(123)I-MIVE scintigraphy. Four of 21 patients showed mixed or no ER blockade. All patients with faint baseline uptake or mixed or no ER blockade after tamoxifen showed progressive disease despite antiestrogen treatment. Patients with clear baseline uptake and complete ER blockade after tamoxifen had a significantly longer progression-free interval (mean +/- SEM, 14.4 +/- 1.6 vs. 1.8 +/- 0.8 mo; P < 0.01).
  
  
  CONCLUSIONS
  Z-(123)I-MIVE scintigraphy seems to be a useful tool to predict response or resistance to antiestrogen treatment in ER-positive metastatic breast cancer patients and to depict nonresponders before the clinical manifestation of progression.
authors.affiliation: Department of Nuclear Medicine, Academic Medical Center, Amsterdam, The Netherlands. r.bennink@amc.uva.nl
authors.forename: Roelof J
authors.initials: RJ
authors.lastname: Bennink
authors.forename: Geertjan
authors.initials: G
authors.lastname: van Tienhoven
authors.forename: Leonie J
authors.initials: LJ
authors.lastname: Rijks
authors.forename: Arnold L
authors.initials: AL
authors.lastname: Noorduyn
authors.forename: Anton G
authors.initials: AG
authors.lastname: Janssen
authors.forename: Gerrit W
authors.initials: GW
authors.lastname: Sloof
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000000981:diagnostic imaging* / Q000378:metabolism*; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000378:metabolism / Q000556:secondary; D018572:Disease-Free Survival; D004958:Estradiol / Q000031:analogs & derivatives*; D020847:Estrogen Receptor Modulators / Q000627:therapeutic use*; D005260:Female; D006801:Humans; D008875:Middle Aged; D011379:Prognosis; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D011960:Receptors, Estrogen / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013629:Tamoxifen / Q000627:therapeutic use*; D016896:Treatment Outcome; D014753:Vinyl Compounds
chemical_list: D020847:Estrogen Receptor Modulators; D019275:Radiopharmaceuticals; D011960:Receptors, Estrogen; D014753:Vinyl Compounds; D013629:Tamoxifen; D004958:Estradiol; C042716:17 alpha-iodovinyl-11 beta-methoxyestradiol