Neuroendocrine investigations

Blood tests

Blood tests give us information on general blood count, biochemistry profile, calcium, fasting gut hormones, chromogranin A, ACTH, cortisol, calcitonin, pituitary hormone screen and oncology markers.

Urine tests

Urine tests are used for 24 hour 5-HIAA and catecholamines (special acid bottle and dietary restrictions).

Imaging studies

We will use imaging studies, including either CT or MRI scanning of the thorax, abdomen and pelvis. However, the ‘gold standard’ imaging modality for metastatic (spread) of neuroendocrine tumour is the Octreotide scan, which is a radioisotope scan. Some patients may also have a Gallium-68 Octreotate PET a new and currently experimental form of somatostatin receptor imaging which appears even more sensitive than the Octreotide scan. Another radioisotope scan that can be helpful in patients with midgut carcinoid tumours is the I-123 MIBG scan. Also, Ga-68 octreotate PET scan is a brand new imaging modality, that may be helpful when the Octreotide scan is indeterminate. 16 FDG-PET scan can be helpful in some patients with high-grade (poorly differentiated NETs).

Patients with intestinal problems may require barium studies or a telescope test of the upper intestine, called endoscopy, or lower intestine, called colonoscopy. Finally, if MEN-1 is suspected, then the pituitary gland should be imaged by CT or MRI.

Biopsies

Biopsies may be undertaken or even the surgical removal of the tumour. For NETs, special stains are performed on the tumour for chromogranin, neuron specific enolase, PGP, gastrin +/- other gut hormones. Ki67 (MIB1) is an important marker of cell proliferation and this should be assessed on all samples.

The histology report should also comment on the differentiation of the tumour and evidence of invasion, e.g. into blood vessels or lymph glands.