Gastrointestinal Carcinoid Tumor Causes and Risk Factors

Gastrointestinal carcinoid tumors develop when neuroendocrine cells in the digestive tract acquire genetic changes that cause them to grow and divide uncontrollably. Neuroendocrine cells are specialized cells that respond to signals from the nervous system by releasing hormones that help coordinate digestion, stomach acid production and intestinal function. Most tumors arise in the small intestine, although they can also develop in the rectum, appendix or stomach. 

Although the exact cause of most gastrointestinal carcinoid tumors is unknown, the risk may increase with advancing age, certain inherited genetic syndromes and certain stomach conditions. The cancer tends to grow slowly and may remain undetected for years before causing symptoms or being discovered during an imaging study or another medical procedure. Although their incidence has increased over time, gastrointestinal carcinoid tumors remain uncommon and account for only a small proportion of gastrointestinal cancers. 

What causes gastrointestinal carcinoid tumors? 

Gastrointestinal carcinoid tumors develop when genetic changes disrupt the normal growth controls of neuroendocrine cells in the digestive tract. Instead of growing, dividing and dying in a regulated manner, the altered cells continue to multiply and eventually form a slow-growing tumor.

The precise cause of most gastrointestinal carcinoid tumors remains unclear. Researchers believe these tumors may develop through a combination of acquired genetic alterations, disruptions in cellular signaling pathways and, less commonly, inherited cancer predisposition syndromes.

Potential biological mechanisms involved in gastrointestinal carcinoid tumor development include:

• Acquired DNA mutations – Some changes that disrupt normal cell regulation develop during a person’s lifetime rather than being inherited. These molecular abnormalities can affect how neuroendocrine cells grow, repair DNA damage and respond to normal biological signals.
• Disrupted cell-signaling pathways – Neuroendocrine cells rely on internal signaling systems to help regulate their growth, hormone release and survival. When these pathways do not function properly, abnormal cells may survive, continue to grow and form tumors.
• Changes affecting tumor-suppressor genes – Tumor-suppressor genes help prevent uncontrolled cell growth. When these genes are altered or stop functioning properly, abnormal neuroendocrine cells may be more likely to form tumors.
• Inherited cancer predisposition syndromes – Most gastrointestinal carcinoid tumors are not inherited. However, certain rare hereditary conditions, such as multiple endocrine neoplasia type 1 (MEN1), can increase the likelihood of developing these and other related endocrine tumors.

What are the risk factors for gastrointestinal carcinoid tumors?  

Most gastrointestinal carcinoid tumors have no clearly identifiable cause. However, researchers have identified several characteristics and medical conditions that may increase the risk. These include:

• Advanced age – Gastrointestinal carcinoid tumors are most often diagnosed in adults 50 to 70 years old, although they can occur at any age.
• Family history of gastrointestinal carcinoid tumors – Having a close relative with a gastrointestinal carcinoid tumor may increase the risk, particularly when an inherited cancer syndrome is present.
• Certain inherited genetic syndromes – Although most gastrointestinal carcinoid tumors are not inherited, rare conditions such as MEN1 can significantly increase the risk.
• Chronic atrophic gastritis and pernicious anemia – These related conditions can reduce stomach acid production and raise gastrin levels, both of which are associated with a higher risk of certain gastric carcinoid tumors.

Which risk factors for gastrointestinal carcinoid tumors are nonmodifiable?

Several recognized risk factors for gastrointestinal carcinoid tumors cannot be changed. Understanding these characteristics may help identify individuals who could benefit from genetic counseling or closer medical surveillance. Nonmodifiable risk factors include:

• Age – Most gastrointestinal carcinoid tumors are diagnosed in middle-aged and older adults.
• Inherited genetic syndromes – Conditions such as MEN1 can significantly increase the risk of developing gastrointestinal neuroendocrine tumors.
• Family history – A family history of gastrointestinal carcinoid tumors may suggest an inherited predisposition.

Which risk factors for gastrointestinal carcinoid tumors are modifiable?

Most established risk factors for gastrointestinal carcinoid tumors are not related to lifestyle choices. However, appropriate management of certain underlying medical conditions may help reduce the effects linked to some gastric carcinoid tumors. Potentially modifiable considerations include:

• Treatment of chronic stomach disorders – Appropriate treatment of chronic atrophic gastritis, pernicious anemia and other conditions affecting stomach acid production may help address risk factors associated with certain gastric carcinoid tumors.
• Ongoing medical follow-up – Individuals with chronic gastrointestinal or endocrine conditions should adhere to the recommended treatment plans and attend regular follow-up appointments to help monitor changes in their health.

One of the World's Best Cancer Hospitals

Moffitt is recognized as a top cancer hospital, ranking high on Newsweek's list of World's Best Specialized Hospitals – Oncology 2026.

Schedule an Appointment

Can gastrointestinal carcinoid tumors be prevented?

Because the causes of most gastrointestinal carcinoid tumors are not fully understood, there is no proven strategy for preventing them. However, the following measures may help identify inherited risk, support earlier diagnosis and facilitate timely treatment:

• Discussing family medical history with a healthcare provider – Individuals with a family history of gastrointestinal carcinoid tumors or inherited cancer predisposition syndromes may benefit from additional evaluation.
• Considering genetic counseling when appropriate – Genetic counseling and testing may help identify inherited conditions associated with an increased risk of gastrointestinal carcinoid tumors.
• Managing chronic stomach disorders – Appropriate treatment of chronic atrophic gastritis, pernicious anemia and related stomach conditions may help address factors associated with certain gastric carcinoid tumors.
• Seeking evaluation for persistent digestive symptoms – Persistent abdominal pain, unexplained diarrhea, blood in the stool, black or tarry stools, unexplained weight loss or changes in bowel habits should be evaluated by a healthcare provider.
• Following recommended surveillance plans – Individuals with hereditary syndromes or other high-risk conditions may benefit from periodic imaging, endoscopic evaluations or other surveillance measures recommended by their healthcare team.

Find the help you need for gastrointestinal carcinoid tumors at Moffitt Cancer Center 

Learning that a gastrointestinal carcinoid tumor may be linked to an inherited condition or an underlying digestive disorder can raise important questions about diagnosis, treatment and long-term care. The multispecialty team in Moffitt’s Gastrointestinal Oncology Program has focused expertise in neuroendocrine tumors and provides comprehensive evaluations and individualized treatment recommendations based on each patient’s unique circumstances.

If you would like to learn more about gastrointestinal carcinoid tumor causes, risk factors or treatment options, you can request an appointment with a specialist at Moffitt by calling 1-888-663-3488 or submitting a new patient registration form online. We do not require referrals.