Researchers in the Netherlands have used positron emission tomography (PET) imaging to determine the heterogeneity of oestrogen receptor (ER) expression in metastatic breast cancer.
Knowledge about varying expression of ER across metastases and surrounding normal tissue in breast cancer patients is scarce, say the authors of the study, which appeared in The Journal of Nuclear Medicine. They, therefore, sought to analyse heterogeneity based on 16α-18F-fluoro-17β-estradiol (18F-FES) PET uptake between and within ER-positive metastatic breast cancer patients, taking into account the site of metastases.
A total of 1,617 metastases, as well as normal tissue, in 91 patients were analysed. It was seen that median tumour uptake varied significantly between patients. The uptake of 18F-FES was higher in bone metastases than in lymph node and lung metastases. In addition, cluster analysis identified three subgroups of patients characterised by particular metastatic sites and 18F-FES PET/CT features. The uptake in surrounding normal tissue varied between patients but was highest in the bones.
The authors concluded that 18F-FES uptake in both tumour and normal tissue is heterogeneous and influenced by the site of metastasis. "Different patterns can be distinguished, possibly identifying biologically relevant ER-positive metastatic breast cancer patient subgroups," said the authors.