Early Detection, Diagnosis, and Staging of Lung Neuroendocrine Tumors

A chest x-ray is often the first imaging test a doctor orders if a lung problem is suspected. It might be able to show if there is a tumor in the lung. But some tumors that are small or are in places where they are covered by other organs in the chest may not show up on a chest x-ray. If your doctor is still suspicious or if something is seen on the chest x-ray, a CT scan may be ordered.

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 and/or belly (abdomen) to see if lung NETs have spread to other organs. It can also be used to guide a biopsy needle into an area of concern.

MRI scans create detailed images of soft tissues in the body using radio waves and strong magnets. A dye (gadolinium) may be injected into a vein before the scan to show details better. An MRI scan sometimes can see cancer that has spread to the liver better than a CT scan.

Scans using small amounts of radioactivity and special cameras can be helpful in looking for lung NETs. They can help find tumors or look for areas of cancer spread if doctors aren’t sure where it is in the body.

Somatostatin receptor targeted PET-CT (SSTR-PET/CT): This test can be helpful in finding lung NETs, but is not always reliable, especially for high-grade tumors. The somatostatin receptor (SSTR) is commonly found on NETs, but some NETs do not have the SSTR and therefore are not seen on SSTR-PET/CT.

To identify the presence of lung NETs, dotatate or dotatoc, man-made molecules that bind to the SSTR, are linked to a radioactive tracer. 68Ga-dotatate, 64Cu-dotatate, and 68Ga-dotatoc are the agents used.

When one of these agents attaches to the SSTR on cancer cells, the radioactive tracer can be seen on a PET scan.

This type of imaging scan can be helpful in two ways:

• It can show doctors where the lung NET is and if the NET has spread to other parts of the body.
• It can show doctors if treating the NET with a somatostatin analog, such as octreotide or lanreotide, or Peptide Receptor Radionuclide Therapy (PRRT) would be helpful.

The SSTR-PET scan can be done with a CT scan to give clearer images. A dye may be injected into your vein before the CT scan to show details better.

Somatostatin receptor targeted PET-MRI (SSTR-PET/MRI): The SSTR-PET scan can be done with an MRI scan, as opposed to a CT scan. The decision on which scan to use is based on which organ needs to be viewed. For example, if there is concern that cancer cells have spread to the liver, SSTR-PET/MRI may be a preferred option.

Bronchoscopy is a procedure a doctor uses to look inside the lungs. This is done with a bronchoscope, a thin, flexible tube with a light and a small camera on the end. The tube is put in through your nose or mouth, down your throat, into your trachea (windpipe), and into the airways (bronchi and bronchioles) of your lungs.

If a tumor is found, small pieces can be removed (biopsied) through the tube. The doctor can also sample cells from the lining of the airways by wiping a tiny brush over the surface of the tumor (bronchial brushing) or by rinsing the airways with sterile saltwater and then collecting it (bronchial washing).

This test uses an endoscope with a small ultrasound probe on the end that is passed down into the windpipe. This probe releases sound waves and then uses the echoes that bounce back to create images.

EBUS can be used to see where a tumor has grown inside the lungs and if certain lymph nodes are enlarged. It can also help the doctor guide a needle into a lymph node, tumor, or another suspicious area to do a biopsy.

You will be sedated for this test, so you will need someone to take you home.

For this type of biopsy, a doctor inserts a thin, hollow needle through the skin over lungs and into the tumor to remove a small piece. This is known as a CT-guided transthoracic needle aspiration. The doctor guides the needle into place using images from CT scans.

Doctors can biopsy a tumor during an endoscopy, such as a bronchoscopy.

Rarely, an endoscopic biopsy or a CT-guided needle biopsy will not be able to get enough tissue to identify the type of tumor. In such cases, surgery may be needed to remove a tissue sample.

Surgical biopsies are done much less often now than in the past, since NETs are mostly diagnosed using needle biopsies.