Review: Receptor Targeted Nuclear Imaging of Breast Cancer

Abstract

Receptor targeted nuclear imaging directed against molecular markers overexpressed on breast cancer (BC) cells offers a sensitive and specific method for BC imaging. Currently, a few targets such as estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), somatostatin receptor (SSTR), and the gastrin releasing peptide receptor (GRPR) are being investigated for this purpose. Expression of these targets is BC subtype dependent and information that can be gained from lesion visualization is dependent on the target; ER-targeting radiotracers, e.g., can be used to monitor response to anti-estrogen treatment. Here we give an overview of the studies currently under investigation for receptor targeted nuclear imaging of BC. Main findings of imaging studies are summarized and (potential) purposes of lesion visualization by targeting these molecular markers are discussed. Since BC is a very heterogeneous disease and molecular target expression can vary per subtype, but also during disease progression or under influence of treatment, radiotracers for selected imaging purposes should be chosen carefully.

Development of Radiotracers for Breast Cancer—The Tumor Microenvironment as an Emerging Target

“…A multitude of different radioligands is currently being developed and investigated, each of them uniquely targeting molecular receptors or intracellular components enabling individual patient-tailored therapy planning [ 1 ]. For this, radionuclides are coupled to ligands which recognize and bind the tumor associated molecules ensuring the precise targeting of cancerous cells which can be used for both therapeutic approaches and also live-monitoring of the treatment efficacy [ 2 ]. The urgent need for tailored approaches yielded development of targeted endogenous radiotherapies as a possible treatment option.…”

Feasibility of 18F-FDG Dose Reductions in Breast Cancer PET/MRI

“…Currently, there are several receptor-specific tracers under investigation, and these offer potential beyond the capabilities of current clinical imaging. For example, there is 16a-18 F-fluoro-17b-estradiol, a fluorinated estradiol targeting the estrogen receptor; radionuclides targeting human epidermal growth factor receptor 2; somatostatin receptor-mediated imaging; and gastrin-releasing peptide receptor imaging, which could be applied for disease characterization, staging, or monitoring of therapy response (35). However, those research questions have to be investigated separately.…”

Incidental finding of a breast carcinoma on Ga-68-DOTA-1-Nal3-octreotide positron emission tomography/computed tomography performed for the evaluation of a pancreatic neuroendocrine tumor

“…Somatostatin receptor expression is higher in estrogen-receptor-positive breast cancer. [ 8 ] Importantly, all 5 somatostatin receptor subtypes have been identified and are variably expressed in primary NST breast tumors, and there seems to exist receptor-specific correlations with histological markers as well as estrogen-receptor and progesterone-receptor levels. [ 9 ]…”