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Everything you need to know about neuroendocrine tumors (NETs)

What Are NETs? What Causes NETs? Symptoms of NETs How Common Are NETs?

Types of NETs What May Happen Long Term? Your Care Team Questions to Ask Your Doctor

Diagnostic Tests Tumor Marker Tests

Imaging Methods Other Tests For NETs

Learn how to cope and live with neuroendocrine tumors (NETs)

Coping With Emotions Talking About NETs Gathering information about NETs Information For Caregivers

How are NETs treated? Liver-directed therapies Carcinoid syndrome treatments What to expect

Diet & Nutrition Keeping Track of Medical Care Traveling with NETs Working with NETs Managing Symptoms & Side Effects Hobbies & Interests Preparing for Imaging Scans Patient App

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What causes NETs?

Like many other cancers, the exact causes of most types of neuroendocrine tumors (NETs) are unknown. This includes gastrointestinal NETs, pancreatic NETs, and lung NETs. In the past, NETs were also referred to as carcinoid tumors, however NETs are now more commonly named after their primary location.

There are some cases where the cause may be known or in rare cases linked to a genetic syndrome. People who have one of the following rare family syndromes have a higher risk of developing NETs:

Multiple endocrine neoplasia type 1 (MEN 1)
Neurofibromatosis type 1
Von Hippel-Lindau syndrome (VHL)

Where do NETs start?

A cancer is usually named after the part of the body where it first started to grow. This is known as the primary site or the primary tumor. If the cancer cells spread from the primary site to another part of the body, it is called a secondary cancer or a metastasis.

In NETs, primary tumors can occur in neuroendocrine cells almost anywhere in the body, but are most commonly found in the gastrointestinal tract (digestive system), pancreas, and lungs.

They can also start in other regions — such as the ovaries and testes — and can spread to the liver or bone.

Compared with other cancers, NETs can be small and may grow slowly over a number of years but some NETs can grow faster than others. NETs do not usually cause noticeable symptoms until the tumors have grown and spread. If the tumor grows larger than 2 cm in diameter, there is more than a 50% chance that it will spread to other parts of the body.

What are the symptoms of NETs? >