Imaging hormone receptors in metastatic breast cancer patients

Imaging hormone receptors in metastatic breast cancer patients

The expression of estrogen receptors (ER), determined in biopsies via immunohistochemistry, is a well-established predictive and prognostic biomarker in breast cancer. Biopsies of metastases are however not always feasible in a patient, as the lesion may be unsafe to biopsy. If one lesion is biopsied, heterogeneity of tumor characteristics amongst lesions throughout the body is still unknown. In vivo imaging of hormone receptors has the potential to guide clinical decision making. The UMCG has extensive experience in PET imaging of ER with the tracer 18F-fluoroestradiol (FES). In this thesis recommendations on the use and interpretation of FES-PET scans for breast cancer patients are described. For instance we show how previous radiation therapy affects FES PET results. And in a clinical pilot study we show that the FES-PET can identify metastases that are less likely to respond to the combination of letrozole plus palbociclib.The search for new biomarkers and drug targets continues, and as such the androgen receptor (AR) is of interest. The role of this receptor in breast cancer is reviewed in this thesis. We show that the AR on metastases can be visualized throughout the body by 18F-fluorodihydrotestosterone (FDHT) PET in breast cancer patients and the effect of an AR-blocker can also be visualized. Prior to further implementation of these novel imaging techniques in routine clinical practice, additional steps are needed. We summarize the route of PET tracers from pre-clinical to first-in-human molecular imaging studies, and the potential steps to implement more PET tracers into clinical practice.

Dissertation: http://hdl.handle.net/11370/f61a04ad-759f-4722-8d58-9d30e8c3af04