Exploring Tumor Biology with Fluorodeoxyglucose– Positron Emission Tomography Imaging in Breast Carcinoma Sandip Basu, MBBS (Hons), DRM, DNB, MNAMS a , Rakesh Kumar, MD b , Ays xe Mavi, MD c , Abass Alavi, MD, MD (Hon), PhD (Hon), DSc (Hon) d, * The value of fluorodeoxyglucose–positron emission tomography (FDG-PET)/computed tomography (CT) in breast carcinoma extends well beyond diag- nostic staging and detection of primary lesions. An association between high FDG uptake and a worse prognosis has been emphasized in the recent literature. Several studies have been or are being performed correlating FDG uptake with various prognostic and molecular biomarkers as well as different parameters predicting tumor response to therapy. Innovative radiotracers for specific imaging of tumoral perfusion (eg, [(15)O]H(2)O), hormone receptor expression (eg, [(18)F]FES), protein synthesis (eg, [(11)C]methionine), and proliferation rate (eg, [(18)F]FLT) provide additional information about tumor characteristics and have been dealt with in detail by Mankoff and colleagues elsewhere in this issue. In this article, the authors have classified the studies investigating FDG-PET imaging in depict- ing breast cancer biology into six different groups based upon the tumor characteristic that was correlated with the FDG uptake in the particular study. These are listed in Box 1 and Table 1. STUDIES INVESTIGATING FDG UPTAKE WITH TUMOR SUBTYPES There has been significant evidence that FDG accumulation in breast cancer is primarily GLUT1-mediated and that the ductal carcinomas are more metabolically active that the lobular subtype (Fig. 1), commensurate with their known aggressive biology compared with the latter. In the study by Buck and colleagues 1 that inves- tigated FDG accumulation in primary breast cancer, FDG uptake was significantly higher in ductal carcinoma than in lobular carcinoma (mean tumor-to-background ratio, 17.3 vs 6.5, respectively). Of all the parameters examined in this study (c-erb B2, tumor grade, estrogen receptor [ER] status, progesterone receptor [PR] status, tumor size, axillary lymph node status, proliferation index, and Ki-67), only Ki-67 showed a Radiation Medicine Centre (BARC), Tata Memorial Hospital Annexe, Parel, Mumbai, India b Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, 110029, India c Department of Nuclear Medicine, Yeditepe University Hospital, Istanbul, Turkey d Nuclear Medicine Section, Radiology Department, Hospital of the University of Pennsylvania, Philadelphia, PA, USA * Corresponding author. E-mail address: abass.alavi@uphs.upenn.edu (A. Alavi). KEYWORDS  FDG-positron emission tomography  Breast carcinoma  Triple-negative cancer PET Clin 4 (2009) 381–389 doi:10.1016/j.cpet.2009.12.001 1556-8598/09/$ – see front matter ª 2009 Elsevier Inc. All rights reserved. pet.theclinics.com