Neuroendocrine Tumor of the Lung: Diagnosis

Approved by the Cancer.Net Editorial Board, 02/2021

ON THIS PAGE: You will find a list of common tests, procedures, and scans that doctors use to find the cause of the medical problem. Use the menu to see other pages.

Doctors use many tests to find, or diagnose, a lung NET. They also do tests to learn if cancer has spread to another part of the body from where it started. If this happens, it is called metastasis. For example, imaging tests can show if the cancer has spread. Imaging tests show pictures of the inside of the body. Doctors may also do tests to learn which treatments could work best.

For most types of cancer, a biopsy is the only sure way for the doctor to know if an area of the body has a tumor. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.

How a lung NET is diagnosed

There are many tests used for diagnosing a lung NET. Not all tests described here will be used for every person. Your doctor may consider these factors when choosing a diagnostic test:

  • The type of tumor suspected

  • Your signs and symptoms

  • Your age and general health

  • The results of earlier medical tests

Most lung NETs are found unexpectedly when people have imaging tests or a medical procedure done for reasons unrelated to the tumor. If a doctor suspects this type of tumor, they will ask you for a complete medical and family history and perform a thorough physical examination. In addition, the following tests may be used to diagnose a lung NET:

  • Biopsy. A biopsy is the removal of a small amount of tissue for examination under a microscope to make a diagnosis of NET. A pathologist then analyzes the sample(s) removed during the biopsy. A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease. Your doctor may recommend running laboratory tests on a tumor sample to identify specific genes unique to the tumor. This testing is less helpful in NETs than in other cancers.

  • Bronchoscopy. This is a type of endoscopy that allows the doctor to see inside the airway and lungs with a thin, lighted, flexible tube called a bronchoscope. The person may be sedated as the tube is inserted through the nose or mouth and into the lungs. Sedation is giving medication to become more relaxed, calm, or sleepy. If an abnormality is found, a biopsy will be performed.

  • Endobronchial ultrasound. An endobronchial ultrasound (EBUS) uses sound waves to create a picture of internal organs. During an EBUS, a machine that produces the sound waves, called a transducer, is inserted through the mouth and windpipe, or trachea, to look at the lungs and lymph nodes. The device is also able to take tissue samples for analysis. EBUS can show enlarged lymph nodes, which may help the doctor find a tumor or figure out the stage of the disease. The person will be sedated during this procedure.

  • X-ray. An x-ray is a way to create a picture of the structures inside the body. A chest x-ray may be taken to look for a lung NET. Sometimes, the tumor may not show up on a chest x-ray because of its size or location, so the doctor may also recommend other types of scans.

  • Computed tomography (CT or CAT) scan. A CT scan takes pictures of the inside of the body using x-rays taken from different angles. A computer combines these pictures into a detailed, 3-dimensional image that shows any abnormalities or tumors. A CT scan can be used to measure the tumor’s size. Additionally, a CT scan is used to see if the tumor has spread to the lymph nodes or to distant sites like the liver. A special dye called a contrast medium is usually given before the scan to provide better detail on the image. This dye is injected into a patient’s vein.

  • Magnetic resonance imaging (MRI). An MRI uses magnetic fields, not x-rays, to produce detailed images of the body. For lung NETs, an MRI of the abdomen (in place of a CT scan) can be used to look for cancer that has spread to other places in the body. A special dye called a contrast medium is given before the scan to create a clearer picture. This dye is injected into a patient’s vein.

  • Nuclear medicine imaging. During this test, a small amount of a radioactive drug, called a tracer, is injected into a patient’s vein. The body is then scanned to show where the radioactivity has built up in the body. The amount of radiation in the tracer is too low to be harmful. PET-CT scans are the type of imaging used for NETs. A PET scan is usually combined with a CT scan (see above), called a PET or PET-CT scan. There are 3 types of tracers used in a PET scan: gallium-68 (68Ga) DOTATATE, copper-64 (64Cu) DOTATATE, and (18F) fluorodeoxyglucose (FDG).

    • 68Ga DOTATATE PET and 64Cu DOTATATE PET are forms of somatostatin receptor imaging and are primarily used to look at slow-growing NETs (grades 1 and 2, see Stages and Grades). Somatostatin receptors are proteins present on the surface of a NET cell that serve as a target for these imaging agents. When the 68Ga or 64Cu attaches to the somatostatin receptor and a picture is taken, cancer spots glow like light bulbs. The 68Ga DOTATATE PET scan has replaced a different method of nuclear imaging called OctreoScan because it is more effective. A 64Cu DOTATATE PET scan is the latest tracer to be made available to locate NETs.

    • 18F FDG PET scan is another type of PET scan, but it does not use the somatostatin receptor. It is sometimes used for faster-growing NETs (grade 3).

  • Blood/urine tests. The doctor may need samples of your blood and urine to check for abnormal levels of hormones and other substances. Urine tests check the amount of 5-HIAA, a product of serotonin breakdown. Serotonin, a neurotransmitter involved in behavior and depression, is made by some NETs. So if a test finds 5-HIAA, the results may suggest that a NET is present. Measurements of serotonin levels may also be taken. In rare cases, a doctor may be able to diagnose a NET from a urine test alone.

After diagnostic tests are done, your doctor will review the results with you. If the diagnosis is a NET, these results also help the doctor describe the tumor. This is called staging.

The next section in this guide is Stages and Grades. It explains the system doctors use to describe the extent of the disease. Use the menu to choose a different section to read in this guide.