Positron emission tomography in breast cancer: 18F- FDG and other radiopharmaceuticals

Abstract

Background: Breast cancer heterogeneity reflects the complex biology of this disease. Breast cancer subtypes, as identified either by immunohistochemistry (IHC) or by gene expression analysis, present different molecular characteristics and prognosis. In this context, molecular imaging techniques providing functional information, contribute in evaluating response to treatment and long-term prognosis among different subtypes. Nuclear imaging diagnosis modalities play an important role for conducting research on cancer biology and developing new treatment approaches. Positron Emission Tomography (PET) is a radionuclide based imaging method that has the potential to locate the tumor, define its staging, and monitor its response to treatment. Results: In the current study, we will review the utility of the most widely used molecular imaging technique, 18F-fluorodeoxyglucose (18F-FDG) PET, in order to determine the relationship between standardized uptake values (SUVs) and immunohistopathological factors, as well as to clarify whether PET is able to predict breast cancer phenotypes. Moreover, we will discuss the rising development of new radiopharmaceuticals in PET imaging, such as 18F-fluoro-17-estradiol (FES), 18F-fluoro-l-thymidine (FLT), 18F-fluoromisonidazole (FISO), and 89Zr-immuno-PET, which give more information about tumor characteristics. Conclusions: In order to improve clinical decision making, enabling hereafter more successful individualized therapies, it is imperative to combine PET radiopharmaceuticals and imaging techniques of critical biologic and pathologic phenomena, including ER, PR and HER2 expression, angiogenesis, hypoxia, apoptosis and metabolic changes in the microenviroment of breast tumors.