Well differentiated neuroendocrine tumour

By Jason Wasserman MD PhD FRCPC
February 8, 2023

What is a well differentiated neuroendocrine tumour?

A well differentiated neuroendocrine tumour (NET) is a type of cancer made up of specialized neuroendocrine cells. The tumour is described as “well differentiated” because the cells in the tumour look very similar to normal, healthy neuroendocrine cells. These tumours can be found almost anywhere in the body. Another name for this type of cancer is well differentiated neuroendocrine neoplasm (NEN).

What are neuroendocrine cells?

Neuroendocrine cells are a specialized type of cell that are found throughout the body. Neuroendocrine cells produce chemicals called hormones that act as a signal to influence the function of nearby cells.

Is a well differentiated neuroendocrine tumour benign or malignant?

All well differentiated neuroendocrine tumours are considered malignant (cancerous) because all have the potential to metastasize (spread) to other parts of the body. However, the risk of metastasis depends on several factors including the type of well differentiated neuroendocrine tumour, the size of the tumour, and the tumour grade.

Where in the body are well differentiated neuroendocrine tumours commonly found?

Well differentiated neuroendocrine tumours are commonly found in the pancreas, lungs, digestive tract (especially the stomach, small intestine, colon, and appendix), skin, breast, kidneys, thyroid gland, and reproductive organs.

How are well differentiated neuroendocrine tumours graded?

There are multiple systems used to grade well differentiated neuroendocrine tumours and the system selected depends on where in the body the tumour started. Most systems divide well differentiated neuroendocrine tumours into three grades – G1, G2, and G3 – based on the number of mitotic figures (tumour cells dividing to create new tumour cells) and Ki67 proliferative index (a test used to count cells able to divide). The grade is important because higher-grade tumours (G2 and G3) are more likely to metastasize (spread) to other parts of the body.

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