Molecular imaging in metastatic breast cancer

Abstract

Breast cancer is the most common cause of cancer death among women worldwide. Therapeutic decisions in breast cancer are based on stage and specific tumour characteristics. In addition to conventional imaging and histopathological evaluation, potentially non-invasive molecular imaging of tumour metabolism (by means of the [18F] fluorodeoxyglucose (FDG)-positron emission tomography, FDG-PET) and known predictive biosensitivity, markers (oestrogen-and progesterone receptor, HER2) can be used for disease evaluation in the future. Molecular imaging provides a functional, dynamic aspect that might be useful for diagnostic purposes, treatment selection, and for monitoring treatment response at a molecular level. This is of particular interest in view of the dynamics of tumour metabolism and biomarker expression during progression and treatment of breast cancer. For staging of recurrent and metastatic breast cancer, FDG-PET imaging of tumour metabolism can be of value in selected cases, with its high sensitivity, but varying specificity. For response monitoring and prognostic evaluation, FDG-PET may be useful, but future studies are required to confirm this. Molecular imaging of tumour HER2 and the oestrogen receptor was shown to be feasible in metastatic breast cancer. Imaging of these biomarkers may allow a more tumour specific detection than with FDG-PET or conventional imaging, but its use in breast cancer staging-or treatment requires further evaluation. Future options for molecular imaging in breast cancer include monitoring of other significant biomarkers (such as the progesterone receptor), or direct treatment evaluation by radiolabelling targeted therapeutic drugs (such as the antivascular endothelial growth factor antibody bevacizumab). To establish molecular imaging in practical (breast) cancer care, more extensive research is needed, but clearly the possibilities are extensive.