This article discusses the important role of nuclear medicine imaging and therapy in the management of neuroendocrine tumours (NETs). Somatostatin receptor scintigraphy has a high impact on patient management versus conventional imaging. Molecular radiotherapy is an important part of the management of patients with NETs. Selection of patients for molecular radiotherapy in NETs is based on uptake on their radionuclide imaging study. The imaging agent has the same mechanism of uptake as the therapeutic agent. Thus, the imaging study preselects patients that are likely to concentrate radiation within their tumours.
IntroductionNeuroendocrine tumours (NETs) represent a spectrum of tumours that can arise from various parts of the body and have variability in clinical presentation. They are often classified by embryonic origin into foregut, midgut and hindgut tumours. Foregut tumours develop in the respiratory tract, thymus, stomach, duodenum and pancreas; midgut tumours develop in the small bowel, appendix, caecum and ascending colon; hindgut tumours develop in the transverse colon, descending colon, sigmoid colon or rectum.1 NETs have a spectrum of presentations, ranging from well differentiated to poorly differentiated tumours, functioning to non-functioning and have variable proliferative activity.2 The tumour differentiation, grading (based on tumour proliferation and mitotic activity) and the site of primary tumour are important factors in making therapeutic decisions in management of NET patients.Unlike many cancers, large proportions of NETs tend to be slow growing and are not associated with increased metabolic activity. These are therefore not visualised on fludeoxyglucose (FDG) positron emission tomography/ computerised tomography (PET/CT). Other functional imaging techniques have thus been employed to stage NETs and determine suitability for molecular radiotherapy. Despite variability in presentation, NETs have similar properties in that the majority of well-differentiated and some high-grade tumours can concentrate neuroamines and have a high degree ABSTRACT Molecular radiotheranostics for neuroendocrine tumours of somatostatin receptor (SSR) expression. This high degree of SSR expression and neuroamine concentration can be exploited both in terms of imaging and therapy with radiolabelled somatostatin analogues and radiolabelled catecholamine analogue meta-iodobenzyl guanidine (MIBG).
3,4Selection of patients for molecular radiotherapy is based on uptake on their radionuclide imaging study. In nuclear medicine, theranostics is a combination of a diagnostic agent and a therapeutic agent where the target imaged/treated is the same. The imaging agent has the same mechanism of uptake as the therapeutic agent. Thus, the imaging study pre-selects patients that are likely to concentrate radiation within their tumours. The imaging and therapeutic radiopharmaceutical forms a theranostic pair. This article discusses the important role of radionculide imaging and radionculide therapy in the management of NETs based ...