Doctors use many tests to diagnose cancer and find out if it has metastasized (spread). Some tests may also determine which treatments may be the most effective. For most types of tumors, a biopsy is the only way to make a definitive diagnosis of cancer. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis. Imaging tests may be used to find out whether the cancer has metastasized. Your doctor may consider these factors when choosing a diagnostic test:

• Age and medical condition
• Type of cancer suspected
• Severity of symptoms
• Previous test results

In addition to a physical examination, the following tests may be used to diagnose a neuroendocrine tumor: 

Biopsy [2]. A biopsy is the removal of a small amount of tissue for examination under a microscope. Other tests can suggest that cancer is present, but only a biopsy can make a definite diagnosis. The sample removed from the biopsy is analyzed by a pathologist (a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease). 

Blood/urine tests. The doctor may need samples of the patient’s blood and urine to check for abnormal levels of hormones and other substances. Urine tests check for increased levels of adrenaline in the body. Large amounts of adrenaline can be a sign of pheochromocytoma. The glucagon stimulation test and clonidine suppression test are blood tests that measure adrenaline levels over a period of time for people who sometimes have symptoms of pheochromocytoma. During the glucagon stimulation test, glucagon (a hormone produced by the pancreas that helps the body process carbohydrates) is injected into a vein, and blood samples are drawn at specific intervals to measure the adrenaline levels. During the clonidine (Catapres) suppression test, a tablet of the drug clonidine is swallowed, and blood samples are taken at regular intervals over the next three hours. Clonidine is used to lower adrenaline levels in the blood, so if these levels do not decrease during testing, it may be a sign of a tumor. Blood pressure and heart rate are carefully monitored during these tests.

X-ray. An x-ray is a way to create a picture of the structures inside of the body, using a small amount of radiation.

Computed tomography (CT or CAT) scan [3]. A CT scan creates a three-dimensional picture of the inside of the body with an x-ray machine. A computer then combines these images into a detailed, cross-sectional view that shows any abnormalities or a tumor. Sometimes, a contrast medium (a special dye) is injected into a vein to provide better detail.

Magnetic resonance imaging (MRI) [4]. An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. A contrast medium may be injected into a patient’s vein to create a clearer picture.

Molecular testing of the tumor. Your doctor may recommend running laboratory tests on a tumor sample to identify specific genes, proteins, and other factors unique to the tumor. Results of these tests will help decide whether your treatment options include a type of treatment called targeted therapy (see Treatment).

Learn more about what to expect when having common tests, procedures, and scans [5].

After these diagnostic tests are done, your doctor will review all of the results with you. If the diagnosis is cancer, these results also help the doctor describe the cancer; this is called staging [6]. Learn more about the first steps to take after a diagnosis of cancer [7].