Diagnosing Gastrointestinal Neuroendocrine Tumors
Gastrointestinal neuroendocrine tumors (GI NETs) are slow-growing tumors that form in the lining of the gastrointestinal (digestive) tract, which includes the esophagus, stomach, small intestine, and colon. It most often occurs in the small intestine, appendix, and rectum.
To diagnose GI NET, doctors may perform several examinations, screening tests, and procedures. These tests help confirm the diagnosis and determine the type, severity, or stage of the tumors.
Specialists involved in diagnosing GI NETs may include:
- Endocrinologists: Doctors who specialize in the diagnosis and treatment of hormonal diseases
- Gastroenterologists: Doctors who specialize in the diagnosis and treatment of conditions involving the digestive (gastrointestinal) system
- Medical oncologists: Doctors who specialize in the diagnosis and treatment of cancers
- Radiologists: Doctors who specialize in examining imaging studies to identify abnormalities and signs of disease.
- Pathologists: Doctors who specialize in examining tissue samples to identify abnormalities, including cancer cells.
Examinations, tests and procedures that may be performed to diagnose GI NETs include:
- Health history: Your doctor will ask about your symptoms and personal and family health history to gather relevant information to understand potential risk factors or genetic predispositions for GI NETs.
- Physical exam: A comprehensive assessment of your body to check for any signs of disease or abnormalities.
- Blood tests: These tests may include analyzing a blood sample to measure the levels of certain substances, such as hormones, which can indicate the presence of neuroendocrine tumors. An unusual amount of a substance can be a sign of disease. In the case of GI NETs, this test is used to help diagnose carcinoid syndrome.
- Urine tests: These tests may include collection of urine over a 24-hour period to measure the levels of substances like 5-HIAA or serotonin, which can be indicators of neuroendocrine tumors.
- Tumor marker test: A sample of blood, urine, or tissue is checked to measure the amounts of certain substances made by organs, tissues, or tumor cells in the body. One such tumor marker is chromogranin A, which has been linked to neuroendocrine tumors when found in increased levels in the body.
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- Imaging studies: These may include:
- Computed tomography (CT) scan: This procedure uses X-rays and a computer to create detailed images of an area inside the body to look for GI NET.
- Magnetic resonance imaging (MRI) scan: This procedure uses magnet and radio waves to create detailed images of organs and bones inside the body to look for GI NET.
- Positron emission tomography (PET) scan: This procedure is performed to specifically detect cancer cells, including neuroendocrine tumor cells. A small amount of radioactive glucose is injected into a vein. The PET scan detects locations of cancer cells because they take up more glucose than normal cells and appear brighter on the PET scan.
- MIBG scan: This procedure uses a small amount of radioactive material injected into a vein. GI NET takes up the radioactive material and can be detected by a device that measures levels of radiation.
- Upper GI Endoscopy: A thin tube with a camera and light is inserted through the mouth to view the upper digestive system to look for GI NET or other abnormalities that may be causing symptoms. The doctor can take a tissue sample (biopsy) during this procedure for testing.
- Capsule endoscopy: A small capsule containing a small camera is swallowed. The camera take pictures as the capsule moves through the gastrointestinal tract.
- Colonoscopy: A thin tube with a camera and light is inserted through the rectum to view the lower part of the digestive system (the colon or large intestine) to look for GI NET or other abnormalities. The doctor can take a tissue sample (biopsy) during this procedure for testing.
- Bone scan: A bone scan may be performed to check if there are rapidly dividing cells, such as cancer cells, in the bone. This can help determine if cancer cells have spread beyond the stomach and intestines
Other examinations, test and procedures may be performed based on initial findings, the type or location of GI NET, and individual factors.
Staging: Staging is a process used to find out how far the cancer has spread. The information gathered from various tests and procedures used to diagnose GI NETs is also used for staging. The stage definitions differ based upon the part of the gastrointestinal tract with GI NET. Generally, staging includes consideration of:
- Tumor size
- Spread to other parts of the body outside of the gastrointestinal tract, such as to the liver or lymph nodes
- Symptoms of more advanced disease, such as carcinoid syndrome or carcinoid heart syndrome
This provides general information about diagnosis of GI NET. It is important to consult with a health care professional to determine the specific examinations, tests and procedures necessary to diagnose and develop a treatment plan for GI NET.