Octreotide is a hormone-like substance that is used to both treat  certain types of NETs and to diagnose or monitor  them using scanning techniques, as we discuss here. In an OctreoScan procedure, octreotide is bound to radioactive indium-111, which, when injected into the bloodstream, attaches to tumour cells that have receptors for somatostatin. Because many neuroendocrine tumours have somatostatin receptors on their surface, the octreotide is able to target these receptors, which then allows doctors to see images of the targeted neuroendocrine tumours and any metastases (areas of cancer spread) that might be present.

Patients being treated with somatostatin analogs (long- or short-acting octreotide or lanreotide) need to advise the imaging facility personnel before being scheduled for an octreotide scan. The timing of this scan may need to be determined according to the medication schedule.

Octreotide scans are also used for evaluating the next steps in treatment, such as determining if peptide receptor radionucleotide therapy (PRRT) might be a reasonable treatment option.