Positron emission tomographic assessment of 'metabolic flare' to predict response of metastatic breast cancer to antiestrogen therapy

Farrokh Dehdashti, Fidelma L. Flanagan, Joanne E. Mortimer, John A. Katzenellenbogen, Michael J. Welch, Barry A. Siegel

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272 Scopus citations


We have investigated whether increased tumor uptake of fluorine-18 fluorodeoxyglucose (FDG) detected with positron emission tomography (PET) early after initiating tamoxifen therapy ('metabolic flare') predicts a hormonally responsive breast cancer. Eleven postmenopausal women with biopsy-proved estrogen receptor-positive (ER+) metastatic breast cancer were studied by PET with FDG and 16α[18F]fluoro-17β-estradiol (FES) before and 7-10 days after initiation of tamoxifen therapy. FDG and FES uptake was evaluated semiquantitatively in 21 lesions. The PET results were correlated with follow-up evaluation. continued until the patient be came unresponsive to hormone therapy (3-24 months). There were seven responders and four nonresponders based on clinical follow-up. None of the responders had a clinical flare reaction, but all demonstrated metabolic flare, with a mean ± standard deviation increase in tumor standardized uptake value (SUV for FDG of 1.4 ± 0.7. No evidence for flare was noted in the nonresponders (change in SUV for FDG -0.1 ± 0.4; P = 0.008 vs. responders). The degree of ER blockade by tamoxifen was greater in responders (mean decrease in SUV 2.7 ± 1.7) than in nonresponders (mean decrease 0.8 ± 0.5) (P = 0.04). The lesions of responders had higher baseline SUVs for FES than did those of three of four nonresponders (≥ 2.2 vs ≤ 1.7). The findings of a metabolic flare by FDG-PET and the degree of ER blockade by FES-PET early after institution of tamoxifen treatment appear to predict responsiveness to antiestrogen therapy in patients with ER+ metastatic breast cancer.

Original languageEnglish
Pages (from-to)51-56
Number of pages6
JournalEuropean Journal of Nuclear Medicine
Issue number1
StatePublished - 1999


  • Breast cancer
  • Estrogen receptor
  • F1uorine-18 fluorodeoxyglucose
  • Flare reaction
  • Positron emission tomography


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