Diagnosis of neuroendocrine tumours (NETs)

Diagnosis is the process of finding out the cause of a health problem. Diagnosing a neuroendocrine tumour (NET) may begin with a visit to your family doctor. Your doctor will ask you about any symptoms you have and may do a physical exam. Based on this information, your doctor may refer you to a specialist or order tests to check for a NET or other health problems.

The process of diagnosis may seem long and frustrating. It’s normal to worry, but try to remember that other health conditions can cause similar symptoms as NETs. It’s important for the healthcare team to rule out other reasons for a health problem before making a diagnosis of a NET.

The following tests are usually used to rule out or diagnose NETs. Many of the same tests used to diagnose cancer are used to find out the stage (how far the cancer has progressed). Your doctor may also order other tests to check your general health and to help plan your treatment.

Your health history is a record of your symptoms, risk factors and all the medical events and problems you have had in the past. Your doctor will ask questions about your history of:

• symptoms that suggest a NET
• multiple endocrine neoplasia type 1 (MEN 1)
• smoking

Your doctor may also ask about a family history of:

• NETs
• risk factors for NETs
• other cancers

A physical exam allows your doctor to look for any signs of a NET. During a physical exam, your doctor may:

• measure your blood pressure
• feel the abdomen for enlarged organs
• examine the lungs

Find out more about a physical exam.

A CBC measures the number and quality of white blood cells, red blood cells and platelets. A CBC is done to check your general health. It is also done to check for anemia from long-term (chronic) bleeding.

Find out more about a complete blood count (CBC)..

Blood chemistry tests measure certain chemicals in the blood. They show how well certain organs are functioning and can help find abnormalities. Blood chemistry tests used to diagnose NETs include the following.

Electrolyte panel measures the level of water in the body, muscle function and other body functions. High or low levels of electrolytes may mean there are problems with certain organs.

Blood sugar (glucose) test measures how well your body uses energy from foods. Abnormal blood glucose levels many mean you have diabetes, problems with the pancreas or a clinical syndrome like Cushing syndrome.

Find out more about blood chemistry tests.

Biochemical markers are substances, including proteins and hormones, measured in the blood or urine that are made and released by the cells of a tumour. An increased amount of certain markers may mean that a person has a neuroendocrine tumour or a hormonal syndrome, such as carcinoid syndrome. Biochemical markers can also be used to check your response to cancer treatment and during follow-up.

Many biochemical markers are measured to help diagnose neuroendocrine tumours. They include the following.

Chromogranin A (CgA) is a protein found throughout neuroendocrine tissues and circulates in the blood. High levels may mean there is a functional or non-functional NET. Most NETs cause increased CgA levels. CgA is often the first biochemical marker used to check for neuroendocrine tumours. A false-positive result may happen if a person is taking a type of medicine called proton pump inhibitors.

5-HIAA (5-hydroxyindoleacetic acid) is a substance made from serotonin and measured in the urine. High levels may mean symptoms are caused by carcinoid syndrome or carcinoid crisis. 5-HIAA is usually the first biochemical marker checked when a person has symptoms of carcinoid syndrome. But many foods and drugs affect the levels of 5-HIAA, so it may show an incorrect result. And some NETs do not make 5-HIAA.

Depending on the symptoms a person is having, other biochemical markers may be tested such as:

• calcitonin
• cortisol
• adrenocorticotropic hormone (ACTH)
• gastrin
• glucagon
• insulin
• somatostatin
• vasoactive intestinal polypeptide (VIP)
• pancreatic polypeptide (PP)
• metanephrines

An ultrasound uses high-frequency sound waves to make images of parts of the body. It is used to check the abdomen for tumours or other abnormalities. It may also be used during an endoscopy or to guide a biopsy needle to a tumour.

An echocardiogram is an ultrasound of the heart. It may be used to check the health of the heart and if any heart damage is developing because of carcinoid syndrome.

Find out more about an ultrasound and an echocardiogram.

A computed tomography (CT) scan uses special x-ray equipment to make 3-D and cross-sectional images of organs, tissues, bones and blood vessels inside the body. A computer turns the images into detailed pictures.

A CT scan is used to:

• check for tumours in the abdomen, pelvis and chest
• find out where the tumours are in those areas
• find out if a NET has spread to the liver
• determine whether surgery can be done

Doctors can also use a CT scan to guide a biopsy needle to a specific area in the body. This is called a CT-guided biopsy.

Find out more about a CT scan.

Magnetic resonance imaging (MRI) uses powerful magnetic forces and radiofrequency waves to make cross-sectional images of organs, tissues, bones and blood vessels. A computer turns the images into 3-D pictures.

An MRI is used to check for tumours and find out where they are in the body. It may be used instead of a CT scan.

Find out more about an MRI.

An octreotide scan is a nuclear medicine imaging test that uses radioactive materials called radiopharmaceuticals to look for NET cells in the body. It is also called an OctreoScan, a somatostatin receptor scintigraphy or an indium 111-pentetreotide scintigraphy. An octreotide scan is commonly used to find out where the NET started and if the cancer has spread to other organs.

The scan uses a drug called octreotide (Sandostatin) that looks and acts like a substance in the body called somatostatin. Somatostatin attaches to receptors on the surface of many NET cells. A form of octreotide is attached to a radioactive material and then injected into the body. The radioactive material gives off a small dose of radiation that can be seen by a special scanner. Several scans are needed to complete the test. A computer makes images of the body to show where the octreotide attached to NET cells.

An MIBG scan is a nuclear medicine imaging test that combines a radioactive material with a substance called metaiodobenzylguanidine (MIBG) to find certain types of tumours in the body. After the radioactive MIBG is injected into the body, the body is scanned and a computer makes images to show where the MIBG has collected. An MIBG scan is also called an MIBG scintigraphy or MIBG scintiscan.

An MIBG scan is used to find certain tumours, such as pheochromocytomas, and where they are in the body.

Find out more about an MIBG scan.

A positron emission tomography (PET) scan uses radioactive materials called radiopharmaceuticals to look for changes in the metabolic activity of body tissues. A computer analyzes the radioactive patterns and makes 3-D colour images of the area being scanned.

A PET scan is used to find tumours and find out if the cancer has spread to other organs. It may be used in some cases when other imaging tests are not clear.

Find out more about a PET scan.

Barium tests use a contrast medium called barium sulphate and x-rays to make pictures of the upper or lower part of the GI tract. They are used to check for tumours and find the cause of GI symptoms. Barium tests used to help diagnose NETs include:

• upper GI series to examine the upper GI tract including the esophagus, stomach and small intestine
• barium enema to examine the lower GI tract including the whole large intestine

Find out more about upper gastrointestinal (GI) series and a barium enema.

An endoscopy is done to check if a tumour is causing symptoms. It allows a doctor to look inside the body using a flexible tube with a light and lens on the end. This tool is called an endoscope.

The type of endoscopy done depends on what part of the body needs to be examined and may include:

• upper GI endoscopy to check the esophagus, stomach and first part of the small intestine (called the duodenum)
• colonoscopy to check the large intestine
• bronchoscopy to check the airways of the lungs

In an endoscopic ultrasound, an ultrasound probe is attached to the end of the endoscope to produce ultrasound images during the endoscopy.

Find out more about an endoscopy, a colonoscopy and a bronchoscopy.

During a biopsy, the doctor removes tissues or cells from the body so they can be tested in a lab. A report from the pathologist will show whether or not cancer cells are found in the sample. The tissue or cells are also examined to determine the features of the tumour, such as the type of hormone released by the tumour and how quickly the cells are dividing and growing.

The type of biopsy done depends on where the tumour is located. Biopsies used to diagnose NETs include the following.

Fine needle aspiration (FNA) uses a very thin needle and syringe to remove cells, tissue or fluid from an abnormal area or lump. It can be used to biopsy a lump that may be a NET.

Core biopsy uses a hollow needle or probe to remove tissue. It is a larger biopsy than an FNA so it is often used when additional tests need to be done on the tumour.

Endoscopic biopsy removes small amounts of tissue or a growth during an endoscopy. It is most often used for tumours in the GI tract or lungs.

Find out more about a biopsy.

A bone scan uses bone-seeking radioactive materials called radiopharmaceuticals and a computer to create a picture of the bones. It is used to find out if neuroendocrine cancer has spread to the bones.

Find out more about a bone scan.

To make the decisions that are right for you, ask your healthcare team questions about a diagnosis.