Tests for Oral Cavity and Oropharyngeal Cancers

A CT scan uses x-rays to make detailed cross-sectional images of your body. Instead of taking 1 or 2 pictures like a regular x-ray, a CT scanner takes many pictures and a computer combines them to show a slice of the part of your body being studied.

A CT scan with contrast of your oral cavity or oropharynx can help determine if the tumor has spread into your bone(s). CT scans can also be used to look for tumors in other parts of your body.

Like a CT scan, an MRI scan shows detailed images of soft tissues in your body. MRI scans use radio waves and strong magnets instead of x-rays. To get clear pictures, a contrast material called gadolinium might be injected into one of your veins before the scan.

Doctors often use MRI to try to find out if the cancer has grown into nearby structures, particularly the soft tissue and nerves. An MRI scan might be done for oral cavity cancer if you have a lot of dental fillings that could distort the pictures in a CT scan.

For a PET scan, a slightly radioactive form of sugar known as fluorodeoxyglucose (FDG) is injected into your blood. It collects mainly in cancer cells because these cells tend to take up more sugar (or glucose) than normal cells.

PET/CT scan

A PET scan is often combined with a CT scan using a special machine that can do both at the same time. This lets the doctor compare areas of higher radioactivity on the PET scan with a more detailed picture on the CT scan.

This is the type of PET scan most often used in people with cancer. Doctors use PET/CT scans to see if and where a cancer has spread (known as staging). This type of scan can be used to look at most organs in the body, but it isn’t useful for looking at the brain or spinal cord.

A barium swallow can be used to see the lining of the upper part of your digestive system, especially your esophagus, which is the tube that connects your throat to your stomach.

For this test, you drink a chalky liquid called barium which coats the walls of your throat and esophagus. A series of x-rays is taken as you swallow. Your doctor may order this test because people with oral and oropharyngeal cancers are at risk for cancer of the esophagus. It is also useful to see if the cancer is causing problems with swallowing.

An ultrasound uses sound waves and their echoes to create images of the inside of the body. A small microphone-like instrument called a transducer gives off sound waves and picks up the echoes as they bounce off organs. The echoes are converted by a computer into an image on a screen.

During a neck ultrasound, a transducer is moved along the skin over your neck. It can help find swollen or abnormal lymph nodes, which can be a sign of cancer. The ultrasound can help guide a needle into the abnormal lymph node for an FNA biopsy. It might also be used after treatment to look for signs of cancer coming back (recurrence).

Small mirrors on long, thin handles are used to look at your throat, the base of your tongue, and part of your larynx (voice box).

A flexible fiber-optic scope called an endoscope is put in through your mouth or nose to look at areas that can’t easily be seen with mirrors, such as behind your nose (nasopharynx) and your voice box (larynx).

It can also help doctors get a clearer look at areas of change that were seen with the mirrors during an indirect pharyngoscopy and laryngoscopy.

Since tobacco and alcohol use are risk factors for oral cavity and oropharyngeal cancers, as well as cancers of the esophagus and lung, there is a chance (up to 10%) of finding more than one cancer at the same time. Doctors might do a panendoscopy to make sure there are no other cancers in your esophagus or lung. This procedure is also helpful if it is unclear where the cancer started or if the lymph nodes in the bottom part of the neck seem abnormal.

It is usually done in an operating room while you are asleep under general anesthesia. During the exam:

• The doctor uses a laryngoscope to look for tumors in your throat and voice box.
• Other parts of your mouth, nose, and throat are examined, too.
• The doctor might also use an esophagoscope to look into your esophagus or a bronchoscope to look into your trachea (windpipe) and bronchi.

For this test, the doctor scrapes the changed area with a stiff brush (brush biopsy) and smears the collected tissue onto a glass slide. The sample is then stained with dye so the cells can be seen clearly. If any of the cells look abnormal, the area can then be biopsied.

The advantage of this test is that it's easy to do and causes very little pain. This can lead to an earlier diagnosis and a greater chance of treatment being successful if cancer is found. This method doesn't show all cancers. Sometimes it’s not possible to tell the difference between cancer cells and abnormal cells that aren't cancer (such as dysplasia), so a different type of biopsy would still be needed.

An FNA biopsy may be used if you have a suspicious lump in or near your neck. To do this, the doctor puts a thin, hollow needle into the lump to remove fluid containing cells or tiny bits of tissue. The cells are then looked at in the lab to see if they are cancer cells.

This type of biopsy can show if an enlarged lymph node in your neck is caused by the spread of cancer from somewhere else or by a cancer that started in your lymph nodes (lymphoma).

If you have already been diagnosed with oral cavity or oropharyngeal cancer and you have enlarged neck lymph nodes, FNA can help find out if the swelling is caused by the spread of the cancer.

This is the most common type of biopsy used to check changes in the mouth or throat. For this procedure, a small piece of tissue is cut from the area that looks abnormal.

The biopsy can be done either in the doctor’s office or in the operating room, depending on the location of the tumor and how easy it is to get a good tissue sample.

• If it can be done in the doctor’s office, the area around the tumor will be numbed.
• If the tumor is deep inside your mouth or throat, the biopsy might be done in the operating room while you are in a deep sleep under general anesthesia.

Biopsy samples are sometimes taken during a panendoscopy. This is usually done as an outpatient procedure and takes place in the operating room while you are under general anesthesia (a deep sleep).

For cancers of the throat, biopsy samples are often tested for the p16 protein to see if HPV infection is present. This is a key part of staging, which is the process of finding out if and how much the cancer has spread.

The presence of HPV infection is considered when making treatment decisions for oropharyngeal cancer. This information can also help doctors predict the probable course of the cancer, because people whose cancers are linked to HPV tend to do better than those whose cancers are not.

If the cancer is advanced, the cancer cells will probably be tested for specific gene and protein changes that might help tell if targeted therapy could be an option for treatment.

The cells may be tested to see if they have high numbers of gene changes called microsatellite instability (MSI). Testing might also be done to check for changes in any of the mismatch repair (MMR) genes (MLH1, MSH2, MSH6, and PMS2) or the proteins they encode.

PD-L1 (programmed death ligand 1) is a protein on cancer cells. The presence of PD-L1 guides decisions about whether a person will benefit from certain immunotherapy drugs.

TMB is a measure of the number of gene changes (mutations) inside the cancer cells. Oral cavity and oropharyngeal cancer cells that have many gene mutations (a high TMB) might be more likely to be recognized as abnormal and attacked by the body’s immune system.

If your tissue is tested and found to have a high TMB (TMB-H), treatment with pembrolizumab (Keytruda) or other immunotherapy might be an option.