Carcinoid Tumor Diagnosis

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Carcinoid tumors are rare, slow-growing neuroendocrine tumors (NETs) that can arise in several places throughout the body. Carcinoid tumors usually begin in the digestive tract (stomach, appendix, small intestine, duodenum, colon, rectum) or in the lungs.

Although less than 10% of people with carcinoid tumors have or develop symptoms, a correct diagnosis is essential to delivering timely and effective treatment of carcinoid tumors. This typically involves a review of your symptoms, a physical exam, and a combination of lab and imaging tests to identify the characteristics of the disease. Your condition would then be staged (categorized by severity) to direct the appropriate course of treatment.

Carcinoid Tumor Diagnosis

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Self-Checks and At-Home Testing

There are no in-home tests or self-exams able to diagnose carcinoid tumors. Therefore, knowing and understanding the signs and symptoms of a carcinoid tumor is essential to communicate them to your doctor. This can greatly increase your chances of having a correct diagnosis and allowing yourself to receive the appropriate treatment as soon as possible.

The symptoms of a carcinoid tumor depend on where it is located in the body and whether certain chemicals and hormones are secreted in the bloodstream. If the carcinoid tumor is located in the digestive tract, symptoms may include:

  • Pain in the abdomen
  • Nausea, vomiting, or constipation
  • Diarrhea
  • Rectal bleeding
  • Rectal pain

If the carcinoid tumor is in the lungs, symptoms may include:

  • Trouble breathing
  • Chest pain
  • Wheezing
  • Redness or a feeling of warmth on the neck (skin flushing)
  • Pink or purple marks on the neck that look like stretch marks

While many of these symptoms can arise from other medical conditions, be sure to get early medical attention if you experience any of these symptoms, particularly if you have a family history of carcinoid tumors.

Labs and Tests

Small carcinoid tumors may be difficult to detect and therefore difficult to diagnose. Often, these tumors are detected during surgery or in an exam for another condition. However, there are tests that can be used to detect carcinoid tumors, which include blood tests, urine tests, and biopsies.

Blood Tests

A blood test may show an increased level of serotonin, which is a hormone and growth factor for several cancer types. Serotonin is also involved in cancer cell migration, metastasis, and angiogenesis (formation of new blood vessels). A blood test can also show high levels of chromogranin A (CgA), which is a substance made by most carcinoid tumors.

Pre-Test Considerations

Keep in mind that some foods, such as bananas, plantains, kiwi fruit, certain nuts, avocado, tomatoes, and eggplant, contain a lot of serotonin and can raise 5-HIAA levels. Medicines, including cough syrup and Tylenol (acetaminophen), can also affect the results. Ask your doctor what you should avoid eating before having a blood test.

Urine Tests

Urine tests are commonly used to look for a more aggressive form of carcinoid tumor known as carcinoid syndrome but can also be used to detect benign (noncancerous) carcinoid tumors. Urine tests measure the levels of 5-HIAA (5-hydroxy indole acetic acid), which is a waste product of serotonin, in a urine sample collected over 24 hours.

These tests can help diagnose many (but not all) carcinoid tumors. However, some carcinoid tumors are small and don’t release enough serotonin for a positive test result.

Pre-Test Considerations

Some foods and medications contain a lot of serotonin and can raise 5-HIAA levels in the urine and blood. Ask your doctor what you should avoid before having urine or blood tests for carcinoid syndrome.

Biopsy

A biopsy is a surgical procedure to test a sample of tissue from the carcinoid tumor and look at it under a microscope. A biopsy can sometimes be done by using a flexible scope to look inside your body. This procedure is called endoscopy.

If a tumor is found, your doctor may take a sample of the tissue for diagnosis.

Imaging

Radiographic and nuclear imaging play important roles in the diagnosis and management of carcinoid tumors. There are five imaging tests commonly used for the diagnosis of carcinoid tumors, which include:

These scans can help your doctor pinpoint the location of a single tumor or multiple carcinoid tumors. Your doctor may also perform an endoscopy to locate carcinoid tumors, bleeding, or infections in the surrounding area.

Chest X-ray

Chest X-rays are an important tool for lung cancer screening.chest X-ray can produce images of your lungs, airways, heart, blood vessels, and bones of the chest and spine. It is often the first imaging test a healthcare provider will order if a lung problem is suspected. 

Chest X-rays are good at detecting larger carcinoid tumors. However, some carcinoid tumors that are small or are located in areas where they are covered by other organs in the chest may not show up on a chest X-ray. If this occurs, your doctor may order additional diagnostic tests, such as CT or MRI.

Computed Tomography (CT)

A CT scan uses X-rays taken from different angles, which are combined by a computer to make detailed pictures of the organs. This test is most often used to look at the chest or abdomen to see if carcinoid tumors have metastasized (spread to other organs). It can also be used to guide a biopsy needle into an area of concern. 

A CT scan is more likely to show small lung tumors than routine chest X-rays. It can also provide precise information about the size, shape, and position of any lung tumors and can help find enlarged lymph nodes that might contain cancer that has spread from the lung.

Magnetic Resonance Imaging (MRI)

MRI is a technology that uses magnetic and radio waves to create highly detailed images, mainly of soft tissue. MRI creates cross-sectional slices (views) to see your body from different angles, including the front, side, and back.

Unlike CT scans, MRI doesn't use radiation. Instead, it uses strong magnets to make the images. Doctors use MRI to find carcinoid cancers in different regions of the body and look for signs that it may have metastasized. This technology can also help doctors plan cancer treatment, like surgery or radiation.

Ga-68 Dotatate PET/CT Scan

For a PET/CT Ga-68 Dotatate Scan (PET scan), a radioactive substance called a tracer is injected into your vein. This tracer is known as Ga-68 dotatate. After the tracer is injected, somastation receptors (which are highly present in carcinoid tumors) take in the tracer. About an hour later, a PET scan and a CT scan are performed. These scans can help your healthcare team see the differences in your cells and identify the presence of a tumor.

Octreoscan

An Octreoscan, or somatostatin receptor scintigraphy, is a special type of scan that can detect carcinoid tumors. This test uses a drug called octreotide bound to a radioactive substance called indium-111 (In-111). Octreotide is a hormone-like substance that attaches to carcinoid cells. In-111 is a diagnostic radiopharmaceutical.

After a small amount of octreotide is injected into a vein, it travels through the blood and is picked up by carcinoid tumors. A few hours after injection, a special camera can be used to show where the radioactivity has been collected in the body. As such, an Octreoscan is generally more sensitive to X-rays and other diagnostic scans, such as CT and MRI.

Scopes and Cameras

To see inside your gastrointestinal tract for carcinoid tumors, your doctor may perform an endoscopy. To find lung carcinoid tumors in the lungs, your doctor may perform a bronchoscopy, which involves passing a scope down your throat and into your lungs.

Your doctor may perform an colonoscopy to search for rectal carcinoid tumors by passing a scope through your rectum. They may also look for carcinoid tumors of the stomach or small bowel (duodenum) by performing an upper endoscopy.

Summary

Carcinoid tumors are rare, slow-growing neuroendocrine tumors that can arise throughout the body, often in the digestive tract or the lungs. There are no in-home tests or self-exams to detect carcinoid tumors. However, there are diagnostic tests that can be done, including blood tests, urine tests, and biopsies.

Radiographic and nuclear imaging can also help diagnose and manage carcinoid tumors. There are five commonly used imaging tests, including chest X-rays, CT scans, MRIs, Ga-68 dotatate PET/CT scan, and Octreoscans. Bronchoscopies, colonoscopies, and endoscopies are also used to check for the presence of tumors.

A Word From Verywell

Carcinoid tumors are relatively rare and, in general, slow growing. Sometimes this cancer can be completely cured, but even when the condition is not curable, it can typically be managed and has a good prognosis. While a tumor or cancer diagnosis can cause stress, anxiety, and depression, it is important to remember that these feelings are normal. Do not be afraid to have open and honest conversations with your healthcare provider about treatment options.

Seeking support from others who are facing a similar diagnosis can also be beneficial, as they can share their experiences with various treatments and provide emotional and psychological support. Therefore, consider finding a community online or in person. If you're unsure where to start, your medical team can provide you with information about reputable groups and associations.

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