Causes, Risk Factors, and Prevention of Lung Neuroendocrine Tumors
Learn about the risk factors for lung neuroendocrine tumors (NETs) and what you might be able to do to help lower your risk.
What causes lung neuroendocrine tumors?
A risk factor is anything that affects your chance of getting a disease such as cancer. Different cancers have different risk factors. Some risk factors, like smoking, can be changed. Others, like a person’s age or family history, can’t be changed.
But having a risk factor, or even many, does not mean that you will get cancer. And some people who get cancer may not have any known risk factors.
Here are some of the risk factors for lung NETs:
Lung NETs occur more often in women than in men. The reasons for this are not known.
Lung NETs are more common in White people than in African Americans, Asian Americans, Hispanics, or Latinos.
Lung NETs are usually found in people about 45-55 years old, which is slightly younger than the average age for other types of lung cancer. They can occur in people of almost any age, including children and adolescents.
People with MEN1, an inherited syndrome, seem to be at increased risk for lung NETs. MEN1 runs strongly in families (autosomal dominant inheritance) and the risk of inheriting the condition from a parent with MEN1 is 50%.
People with MEN1 are also at high risk for tumors in certain endocrine organs, such as the pancreas and the pituitary and parathyroid glands.
Most people with lung NETs do not have a family history of this type of cancer but having others in your family who had lung NETs can increase your risk. In rare cases, several family members have been diagnosed with this cancer. The overall risk is still low because this cancer is so uncommon.
Typical lung NETs do not seem to be linked with smoking or with any known chemicals in the environment or workplace. But some studies have found that intermediate-grade (atypical) lung NETs may be more common in people who smoke.
What causes lung neuroendocrine tumors?
Not much is known about what causes lung NETs. Researchers have learned about how certain risk factors like cancer-causing chemicals or radiation can cause changes in lung cells that lead to carcinomas, the more common type of lung cancer. But these factors are not thought to play a large role in the development of lung NETs.
Tumorlets
NETs probably develop from tiny clusters of neuroendocrine cells called carcinoid tumorlets in the lung airways. Tumorlets are sometimes found unexpectedly in lung biopsies done to treat or diagnose other conditions. In the lab, tumorlets resemble NETs, except that they are much smaller – less than 5 mm (about ¼ inch) across. Most tumorlets never grow any bigger, but some may eventually become NETs.
If tumorlets are found throughout the lung along with an overgrowth of neuroendocrine cells, this is called diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIPNECH). Patients with DIPNECH often have asthma-like symptoms, such as cough, wheezing, and shortness of breath. If DIPNECH is found on a biopsy sample, this may mean a lung NET might develop.
However, lung NETs can also develop without DIPNECH being present.
Gene changes
Researchers have found some common genetic changes inside lung NET cells, which might affect how these cells function. It is still unclear exactly how these changes cause carcinoid tumorlets or NETs.
Can lung neuroendocrine tumors be prevented?
Because we do not yet know what causes most lung NETs, it is not possible to know how to prevent them.
Smoking has been linked with an increased risk of intermediate-grade (atypical) lung NETs in some studies, so quitting or not starting might reduce a person’s risk.
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Developed by the American Cancer Society medical and editorial content team with medical review and contribution by the American Society of Clinical Oncology (ASCO).
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Last Revised: December 17, 2025
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