Understanding neuroendocrine cancer

NET and NEC describe different diseases

In the digestive system, specialists distinguish well-differentiated neuroendocrine tumors (NETs) from poorly differentiated neuroendocrine carcinomas (NECs). Differentiation describes the cells' appearance and organization under a microscope.

Well-differentiated NETs have a range of behaviors. Some grow slowly; others grow more quickly. They can be low, intermediate, or high grade. Poorly differentiated NECs are high-grade cancers and generally behave more aggressively. A high-grade NET and a poorly differentiated NEC are separate diagnoses that can require different treatment approaches. NANETS: High-grade neuroendocrine neoplasm consensus recommendations

Symptoms do not tell the whole story

A gastrointestinal NET may cause no early symptoms. When symptoms develop, they can reflect the tumor's location or hormones it releases. Abdominal discomfort and diarrhea are examples, but many other conditions can cause these symptoms. Some hormone-producing gastrointestinal NETs cause carcinoid syndrome, which may include flushing and diarrhea. Symptoms alone cannot establish a diagnosis. NCI: Gastrointestinal neuroendocrine tumors

How the diagnosis is clarified

Evaluation may bring together the medical history, examination, laboratory tests, imaging, and a biopsy. A pathologist examines tissue to identify the disease. An abnormal blood test alone does not prove cancer, and a normal result does not rule it out. Ask your care team to explain how the different findings fit together. NCI: How cancer is diagnosed

Start with three separate questions

Where did the tumor begin? What does the pathology show about its type and grade? Where is it present in the body?

The last question concerns stage, which describes extent and spread. Stage and grade answer different questions. In particular, stage IV describes distant spread; it does not, by itself, establish that the tumor is high grade. NCI: Cancer staging