Abstracts

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E1141. Going Beyond FDG-PET: The Next Generation of Targeted Nuclear Medicine Imaging for Breast Cancer
Authors
  1. Joelle Harwin; University of California - San Francisco
  2. Gary Ulaner; Memorial Sloan Kettering Cancer Center
  3. Ella Jones; University of California - San Francisco
  4. Courtney Lawhn Heath; University of California - San Francisco
  5. Robert Flavell; University of California - San Francisco
  6. Spencer Behr; University of California - San Francisco
  7. Bonnie Joe; University of California - San Francisco
Background
18F-fluorodeoxyglucose positron emission tomography (FGD-PET) is useful for imaging many subtypes and stages of breast cancer. However, breast cancer is a complex and heterogeneous disease resulting in varied imaging appearances. FDG-PET has limitations in characterizing certain subtypes of breast cancer including low grade disease, lobular breast cancer, and some estrogen receptor positive tumors. Besides glucose uptake, there are multiple additional intracellular and extracellular targets which may be useful in evaluating breast cancer. Novel molecular targets for PET imaging in breast cancer may help in characterizing certain breast cancers where FDG-PET has limitations. These novel molecular targets include cell surface receptors, intracellular processes, such as DNA repair and apoptosis, and tumor microenvironment.

Educational Goals / Teaching Points
1. Indications and limitations of FDG-PET in breast cancer 2. Highlight crucial intracellular and extracellular pathophysiology in breast cancer 3. Introduce three emerging categories of novel molecular PET targets in breast cancer: 1. Cell surface receptors 2. Intracellular processes 3. Tumor microenvironment 4. Receptor status may differ between the primary tumor and sites of metastasis. Receptor targeted PET allows simultaneous and non-invasive assessment of whole-body receptor status, often resulting in therapy modification 5. Indications and clinical impact of, recently FDA approved, 18F-fluoroestradiol in breast cancer

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Discuss indications and limitations of FDG-PET in breast cancer. Highlight intracellular and extracellular processes in breast cancer, which may provide molecular targets for PET, as categorized into cell surface receptors (for example, 89Z-trastuzumab targeting HER2), intracellular processes (for example, 18F-annexin as a marker of apoptosis), and tumor microenvironment (for example, 68Ga-FAPI targeting cancer-associated fibroblasts). Use of these novel agents in breast cancer evaluation will be demonstrated through patient cases, some from literature and others which have never been published. We will briefly highlight some landmark trials demonstrating the clinical impact of select PET agents. Discuss recently FDA approved, 18F-fluoroestradiol, highlighting relevance to clinical practice and therapy.

Conclusion
FDG-PET is useful in evaluating breast cancer. However, it has limitations in assessing certain subtypes and stages of breast cancer. Novel molecular targets for PET imaging in breast cancer are being evaluated; including cell surface receptors, intracellular processes, and tumor microenvironment. These novel molecular agents may allow for more targeted and personalized therapy.