Well-differentiated neuroendocrine tumors: a review covering basic principles to loco-regional and targeted therapies

Abstract

Neuroendocrine tumors (NETs) are a complex group of malignancies with variable prognosis and response to treatment. For pancreatic neuroendocrine and carcinoid tumors, traditional cytotoxic chemotherapies have demonstrated minimal activity. Current approaches for treatment of metastatic disease use a combination of loco-regional and targeted biological therapies. Clinical trials remain critical for evaluation of new and promising therapeutic options for patients with NETs.

Figure 1

Computed tomography (CT) scan imaging for neuroendocrine tumors. (a) Selected axial CT images of a patient with a large pancreatic primary neuroendocrine carcinoma and multiple hepatic metastases (top and bottom). (b) CT axial image after right lobar hepatic transarterial chemoembolization (TACE) for liver metastases (top) with three-dimensional reconstruction and subtracted view (bottom).

Figure 2

Octreoscan imaging for neuroendocrine tumors. Coronal octreoscan image demonstrating radiotracer uptake in multiple liver metastases and a large pancreatic primary neuroendocrine carcinoma. (b) Coronal octreoscan fusion images with single positron emission tomography (SPECT) providing increased anatomic detail. (c) Axial octreoscan fusion images with SPECT.

Figure 3

Histological subtypes of neuroendocrine tumors. (a) Microscopic section from a well-differentiated neuroendocrine carcinoma demonstrating low mitotic rate and low-grade bland histology. (b) Microscopic section from a poorly differentiated neuroendocrine carcinoma demonstrating high mitotic rate and high-grade histology similar in appearance to small cell carcinomas.