Neuroendocrine neoplasm (NEN)

A neuroendocrine neoplasm is a type of cancer that develops from specialized neuroendocrine cells. These cells are unique because they share characteristics of both nerve cells and hormone-producing (endocrine) cells. Neuroendocrine neoplasms can develop anywhere in the body where neuroendocrine cells normally reside, including the lungs, stomach, intestines, pancreas, and various glands. The normal function of these cells is to produce hormones that help regulate important body functions, such as digestion, breathing, and blood sugar levels. A neuroendocrine neoplasm occurs when these cells grow and divide uncontrollably, forming a tumour.

Is a neuroendocrine neoplasm the same as a neuroendocrine tumor?

The terms “neuroendocrine neoplasm” and “neuroendocrine tumor” are closely related but have slightly different meanings. The term neuroendocrine neoplasm includes all abnormal growths arising from neuroendocrine cells, regardless of whether they are slow-growing or fast-growing. In contrast, neuroendocrine tumor (NET) is typically used to describe slower-growing, less aggressive types of neuroendocrine neoplasms. The faster-growing, more aggressive types are usually called neuroendocrine carcinomas (NEC). Together, NETs and NECs are part of the larger group called neuroendocrine neoplasms.

Is neuroendocrine neoplasm a type of cancer?

Yes, neuroendocrine neoplasms are considered a type of cancer because they involve the abnormal, uncontrolled growth of cells. However, their behavior can vary widely:

• Neuroendocrine tumors (NETs) tend to grow slowly, and many behave less aggressively, sometimes remaining stable for years.

• Neuroendocrine carcinomas (NECs) are usually aggressive and may grow quickly, spreading rapidly to other body parts.

Pathologists carefully examine each neuroendocrine neoplasm to determine whether it is a slow-growing tumor or a more aggressive carcinoma.

How is this diagnosis made?

The diagnosis of a neuroendocrine neoplasm usually begins with a biopsy, where a small sample of tissue is taken from the tumor and examined under a microscope by a pathologist. The pathologist looks for special features typical of neuroendocrine cells, such as their distinctive appearance and growth pattern. The cells in neuroendocrine neoplasms are often uniform in shape, with small, round nuclei, and may form characteristic groups or clusters.

Pathologists often perform additional tests, such as immunohistochemistry, to confirm that the cells are neuroendocrine in origin.

What other tests may be used to confirm the diagnosis?

Several additional tests can be used to confirm a diagnosis of neuroendocrine neoplasm and to help guide treatment:

• Immunohistochemistry (IHC): This technique uses special antibodies to detect proteins typically found in neuroendocrine cells, such as chromogranin, synaptophysin, CD56, and INSM1. Positive staining for these markers strongly supports the diagnosis.

• Ki-67: Pathologists use the Ki-67 protein to measure how fast the tumor cells are dividing. Higher Ki-67 levels generally mean the tumor grows quickly and may be more aggressive.

• Hormone testing: Blood tests might be performed to detect hormones produced by certain neuroendocrine tumors. For example, serotonin or insulin levels can sometimes help identify specific types of neuroendocrine tumors.

• Molecular tests and genetic sequencing: In some cases, additional genetic testing may be performed to identify specific gene changes or mutations in the tumor cells. This can help determine prognosis or potential treatment options.

These tests help ensure an accurate diagnosis, determine the tumor’s behavior, and guide your healthcare team in selecting the best possible treatment.