Carcinoid Tumor

What is carcinoid tumor?

A carcinoid tumor is a slow-growing type of cancer that starts in neuroendocrine cells. Neuroendocrine cells are special cells found throughout the body that receive signals from the nervous system and respond by releasing hormones — chemical messengers that help control body functions such as digestion, blood flow, and breathing. Because these cells are located in many organs, a carcinoid tumor can appear in different parts of the body. The most common sites are the digestive tract (including the small intestine, appendix, rectum, and stomach) and the lungs.

When people ask what is carcinoid tumor in simple terms, a helpful way to think about it is this: it is a cancer that usually grows slowly and, in many cases, causes few or no symptoms for years. Doctors classify carcinoid tumors as a type of neuroendocrine tumor (often abbreviated NET). The medical code ICD-10 C7A.00 refers to a malignant carcinoid tumor of an unspecified site, meaning the exact location has not been stated in the record.

Although a carcinoid tumor is a form of cancer, its behavior can differ greatly from more aggressive cancers. Some carcinoid tumors remain small and localized for a long time, while others can grow into surrounding tissue or spread (metastasize) to other organs, most often the liver. Carcinoid tumors can occur in adults of any age and are also occasionally found in younger people, sometimes discovered by chance during an unrelated operation such as appendix removal.

Symptoms of carcinoid tumor

Carcinoid tumor symptoms vary widely depending on where the tumor is located, how large it is, and whether it releases hormones into the bloodstream. Many carcinoid tumors cause no symptoms at all, especially in early stages, and are discovered incidentally during imaging, surgery, or endoscopy performed for another reason.

When symptoms do occur, they may include:

• Digestive tract carcinoid tumors: abdominal pain or cramping, diarrhea, nausea, changes in bowel habits, rectal bleeding, or symptoms of bowel blockage such as bloating and vomiting.
• Lung carcinoid tumors: persistent cough, wheezing, coughing up blood, chest discomfort, or repeated lung infections in the same area of the lung.
• Flushing: sudden redness or warmth of the face and neck, sometimes triggered by stress, alcohol, or certain foods.
• Unexplained weight loss or fatigue in some cases.

A smaller group of patients develops a collection of symptoms called carcinoid syndrome. This happens when the tumor releases hormone-like substances — most notably serotonin, a chemical involved in mood and digestion — directly into the general circulation. Carcinoid syndrome typically occurs when the tumor has spread to the liver, because the liver normally breaks down these substances before they reach the rest of the body. Typical features of carcinoid syndrome include episodes of skin flushing, chronic diarrhea, wheezing, and a rapid heartbeat. Over time, some people with carcinoid syndrome develop carcinoid heart disease, in which the heart valves become thickened and stiff, leading to breathlessness and swelling of the legs.

How symptoms differ by stage is important to understand. In early or localized disease, symptoms are often absent or vague and related only to the tumor’s location. In more advanced disease, especially with spread to the liver, hormone-related symptoms such as flushing and diarrhea become more likely. Because early carcinoid tumor symptoms can resemble common conditions such as irritable bowel syndrome or asthma, diagnosis is sometimes delayed. If you have persistent, unexplained symptoms like those listed above, it is reasonable to discuss them with your doctor.

Causes and risk factors

The exact carcinoid tumor causes are not fully understood. Like most cancers, carcinoid tumors develop when neuroendocrine cells acquire changes (mutations) in their DNA that allow them to grow and divide abnormally. In the majority of cases, doctors cannot identify a single cause, and the tumor appears to arise sporadically — meaning by chance, without a clear inherited or environmental trigger.

Several factors are associated with a higher chance of developing a carcinoid tumor:

• Inherited genetic syndromes. A condition called multiple endocrine neoplasia type 1 (MEN1) — an inherited disorder that causes tumors in hormone-producing glands — increases the risk of certain neuroendocrine tumors. Other rare inherited conditions, such as neurofibromatosis type 1, have also been linked to a higher risk.
• Family history. Having a close relative with a carcinoid tumor or another neuroendocrine tumor may modestly increase risk.
• Certain stomach conditions. Long-standing conditions that raise levels of the hormone gastrin, such as atrophic gastritis (chronic thinning and inflammation of the stomach lining) or pernicious anemia (a vitamin B12 deficiency caused by an autoimmune stomach problem), are associated with some stomach carcinoid tumors.
• Age and sex. Carcinoid tumors are most often diagnosed in middle-aged and older adults, though they can occur at any age. Some studies suggest small differences in frequency between men and women depending on the tumor site.

It is important to note that having one or more risk factors does not mean a person will develop a carcinoid tumor, and many people diagnosed with one have no known risk factors at all. There is no proven way to prevent carcinoid tumors, and they are not known to be caused by lifestyle factors in the way some other cancers are.

Diagnosis

Carcinoid tumor diagnosis often involves several steps, because these tumors can be small, slow-growing, and located deep within the body. Doctors typically combine a careful medical history and physical examination with laboratory tests, imaging studies, and a tissue sample (biopsy).

Laboratory tests

Because many carcinoid tumors release hormones or hormone breakdown products, blood and urine tests can provide important clues:

• 24-hour urine test for 5-HIAA. 5-HIAA (5-hydroxyindoleacetic acid) is a breakdown product of serotonin. Elevated levels in the urine collected over a full day can suggest a hormone-producing carcinoid tumor. Certain foods, such as bananas and tomatoes, and some medications can affect the result, so your doctor may ask you to avoid them before the test.
• Chromogranin A blood test. Chromogranin A is a protein released by many neuroendocrine tumors. Raised levels can support the diagnosis and may be used to monitor the disease over time, although other conditions and some medications can also raise this marker.

Imaging studies

Imaging helps doctors locate the tumor, measure its size, and check whether it has spread:

• CT (computed tomography) and MRI (magnetic resonance imaging) scans create detailed pictures of internal organs and are commonly used to find the primary tumor and assess the liver and lymph nodes.
• Somatostatin receptor imaging. Many carcinoid tumor cells carry receptors — docking sites on the cell surface — for a hormone called somatostatin. Special nuclear medicine scans use a mildly radioactive tracer that binds to these receptors, making the tumor visible. Modern versions of this test are often combined with PET-CT imaging, which merges functional and anatomical pictures in a single scan and can detect small tumor deposits that other scans may miss.
• Endoscopy. A thin, flexible tube with a camera can be used to look directly inside the stomach, bowel, or airways and to take tissue samples. Endoscopic ultrasound, which combines endoscopy with ultrasound, can show how deeply a tumor has grown into the wall of the digestive tract.

Biopsy and grading

A definitive diagnosis requires a biopsy — the removal of a small piece of tumor tissue for examination under a microscope. A pathologist (a doctor who specializes in analyzing tissue) confirms that the cells are neuroendocrine and assigns a grade, which describes how quickly the cells appear to be dividing. Low-grade tumors tend to grow slowly, while higher-grade tumors behave more aggressively. Grading, together with staging (determining how far the tumor has spread), guides treatment decisions.

Treatment options

Carcinoid tumor treatment depends on the tumor’s location, size, grade, whether it has spread, whether it is causing hormone-related symptoms, and the patient’s overall health. Because these tumors are relatively uncommon and can behave in different ways, care is usually planned by a multidisciplinary team that includes surgeons, medical oncologists (cancer specialists who use medications), endocrinologists, gastroenterologists, and nuclear medicine specialists. In many hospital systems, including Acibadem, ongoing drug-based cancer care for this condition is coordinated through the Medical Oncology Department.

Surgery

Surgery is the main treatment for carcinoid tumors that are localized — confined to the place where they started. When the entire tumor can be removed, surgery may be curative in many cases. The type of operation depends on the tumor’s location; for example, a small tumor of the appendix may be treated by removing the appendix alone, while a tumor of the small intestine may require removing a segment of bowel and nearby lymph nodes. Even when the tumor has spread, surgeons sometimes remove as much tumor as possible (a procedure called debulking) to reduce hormone symptoms and slow disease progression.

Watchful waiting (active surveillance)

For some very small, low-grade tumors — particularly certain small rectal or stomach carcinoids — doctors may recommend careful monitoring with periodic scans and endoscopy rather than immediate treatment. This approach, often called active surveillance, is considered when the risk of the tumor causing harm appears low and the risks of treatment may outweigh the benefits. Your care team will explain whether this is a reasonable option in your specific situation.

Medications

• Somatostatin analogs. These are laboratory-made versions of the natural hormone somatostatin. Given as regular injections, they can reduce hormone release from the tumor, relieving flushing and diarrhea, and in many cases they also slow tumor growth. They are a cornerstone of treatment for advanced, hormone-producing carcinoid tumors.
• Targeted therapy. These are drugs designed to block specific pathways that tumor cells use to grow. Some targeted medications are approved for certain advanced neuroendocrine tumors; your oncologist can explain whether one is appropriate for your tumor type.
• Chemotherapy. Traditional chemotherapy — drugs that kill rapidly dividing cells — is generally less effective against slow-growing carcinoid tumors but may be considered for higher-grade or rapidly progressing disease.

Nuclear medicine and liver-directed treatments

For tumors that carry somatostatin receptors and have spread, a treatment called peptide receptor radionuclide therapy (PRRT) may be an option. PRRT delivers a small dose of radiation directly to tumor cells by attaching a radioactive particle to a molecule that binds the tumor’s somatostatin receptors. When the disease has spread mainly to the liver, doctors may also consider liver-directed procedures, such as blocking the blood supply to liver tumors (embolization) or destroying individual tumors with heat (ablation).

Managing carcinoid syndrome

Treating hormone-related symptoms is an important part of care. In addition to somatostatin analogs, doctors may recommend medications that reduce serotonin production, dietary adjustments, and avoiding personal triggers such as alcohol or stress. Patients with carcinoid heart disease may need care from a cardiologist and, in some cases, heart valve surgery.

Living with carcinoid tumor and outlook

The outlook for people with a carcinoid tumor varies considerably and depends on the tumor’s location, grade, and stage at diagnosis. In general, carcinoid tumors tend to grow more slowly than many other cancers. When the tumor is found early and removed completely, the long-term outlook is often favorable. Even when the disease has spread, many people live for years with treatment that controls tumor growth and hormone symptoms. However, no doctor can guarantee an outcome, and each person’s situation is different; your care team is the best source of information about your individual prognosis.

Living well with a carcinoid tumor usually involves regular follow-up, which may include periodic blood or urine tests, imaging scans, and endoscopy. Long-term monitoring is important because these tumors can recur or progress slowly over many years. Practical steps that many patients find helpful include:

• Keeping a symptom diary, especially for flushing or diarrhea, to identify personal triggers.
• Discussing diet with your care team, since some foods can worsen carcinoid syndrome symptoms in certain people.
• Attending all scheduled follow-up appointments, even when feeling well.
• Seeking emotional support — living with a slow-growing cancer over many years can be psychologically demanding, and counseling or patient support groups may help.

Frequently asked questions

What is a carcinoid tumor in simple terms?

A carcinoid tumor is a usually slow-growing cancer that starts in neuroendocrine cells — cells that release hormones in response to nerve signals. It most often develops in the digestive tract or lungs. Many carcinoid tumors cause few symptoms for a long time, and some are found by chance during tests or surgery done for other reasons.

Is a carcinoid tumor cancer?

Yes. Carcinoid tumors are classified as malignant, meaning they are a form of cancer, although their behavior is often less aggressive than many other cancers. Some remain small and localized for years, while others can spread to lymph nodes, the liver, or other organs. This is why medical evaluation and follow-up are important even for small tumors.

Can a carcinoid tumor be cured?

In many cases, when a carcinoid tumor is found early and completely removed by surgery, no further disease develops and the treatment can be considered curative. When the tumor has spread, a complete cure is less likely, but treatments can often control the disease and its symptoms for extended periods. Your doctors can explain what is realistic in your specific case.

How serious is a carcinoid tumor?

Seriousness depends on the tumor’s location, grade, and stage. Small, low-grade, localized tumors often carry a favorable outlook, while advanced disease that has spread — especially with carcinoid syndrome or carcinoid heart disease — requires more intensive, long-term management. Because outcomes vary so widely, it is best to discuss your individual situation with your care team rather than rely on general statistics.

What are the first symptoms of a carcinoid tumor?

Early carcinoid tumor symptoms are often vague or absent. When present, they may include abdominal pain, diarrhea, or changes in bowel habits for digestive tract tumors, and cough or wheezing for lung tumors. Episodes of facial flushing can also be an early clue in some people. Because these symptoms overlap with common, less serious conditions, persistent or unexplained symptoms deserve medical evaluation.

How is a carcinoid tumor diagnosed?

Carcinoid tumor diagnosis usually combines blood and urine tests for hormone markers (such as 5-HIAA and chromogranin A), imaging studies such as CT, MRI, or somatostatin receptor PET-CT scans, and endoscopy where appropriate. A biopsy — examining a tissue sample under a microscope — is needed to confirm the diagnosis and determine the tumor’s grade.

What is recovery like after carcinoid tumor treatment?

Recovery depends on the treatment received. After surgery, most people gradually return to normal activities over weeks, though this varies with the extent of the operation. Patients on long-term medications such as somatostatin analogs typically continue normal daily life with regular injections and check-ups. Whatever the treatment, ongoing follow-up with scans and laboratory tests is usually recommended for many years, because carcinoid tumors can recur slowly over time.

When to see a doctor

Make an appointment with your doctor if you experience persistent, unexplained symptoms such as ongoing diarrhea, recurring abdominal pain, repeated episodes of facial flushing, a long-lasting cough, or wheezing that does not respond to usual treatment. If you have already been diagnosed with a carcinoid tumor, contact your care team promptly if your symptoms change or worsen.

Seek urgent medical attention if you notice any of the following red-flag warning signs:

• Severe abdominal pain with vomiting, bloating, or inability to pass stool or gas — possible signs of a bowel blockage.
• Coughing up blood or sudden, severe shortness of breath.
• Significant rectal bleeding or black, tarry stools.
• Sudden severe flushing with dizziness, confusion, a very fast heartbeat, or fainting — possible signs of a serious hormone-related reaction sometimes called carcinoid crisis.
• New or worsening swelling of the legs and breathlessness, which may suggest a heart problem.
• Unintended, rapid weight loss.

These symptoms do not necessarily mean you have a carcinoid tumor, but they warrant prompt medical assessment. Early evaluation gives doctors the best chance to identify the cause and, if a carcinoid tumor is found, to begin appropriate treatment as early as possible.