Salivary Gland Cancer Tests

Salivary gland cancer is most often diagnosed when a person goes to a doctor because of symptoms they are having.

If you have signs or symptoms that might be caused by a salivary gland tumor, your doctor will examine you and order tests to find out if they're being caused by cancer or some other condition. If cancer is found, more tests may be done.

Medical history and physical exam

Usually the first step is to ask you questions about your medical history. The doctor will ask about your symptoms and when they first appeared. You might also be asked about your possible risk factors for salivary gland cancer and about your general health.

During the physical exam, your doctor will carefully examine your mouth and the areas on the sides of your face and around your ears and jaw. The doctor will feel for enlarged lymph nodes (lumps under the skin) in your neck.

The doctor will also check for numbness or weakness in your face (which can happen if cancer spreads into nerves).

Complete head and neck exam

If there is a reason to think you might have cancer, your doctor will refer you to a specialist. These specialists are oral and maxillofacial surgeons or head and neck surgeons. They are also known as ear, nose, and throat (ENT) doctors or otolaryngologists. The specialist will most likely do a complete head and neck exam, as well as order other exams and tests.

The specialist will pay careful attention to the head and neck area, being sure to look and feel for any abnormal areas. This exam will include the lymph nodes in your neck, which will be checked carefully for any swelling.

Because salivary glands are throughout the mouth and throat, some are deep inside the neck and some parts that are not easy to see. The doctor may use mirrors or special fiber-optic scopes to look at these areas. These exams can be done in the doctor’s office. The doctor may first spray the back of your throat with numbing medicine to help make the exam easier.

• Indirect pharyngoscopy and laryngoscopy: Small mirrors on long, thin handles are used to look at your throat, the base of your tongue, and part of the larynx (voice box).
• Direct (flexible) pharyngoscopy and laryngoscopy: 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. It can get a clearer look at areas of change that were seen with the mirrors and also the part behind the nose (nasopharynx) and the larynx (voice box).

Types of salivary gland biopsies

Symptoms and the results of exams or imaging tests may strongly suggest you have salivary gland cancer, but the actual diagnosis is made on a biopsy sample by a pathologist (a doctor who specializes in diagnosing and classifying cancer by testing and looking at cells in the lab). Different types of biopsies might be done, depending on the situation.

Fine needle aspiration (FNA) biopsy

An FNA biopsy takes a small amount of cells and fluid from a lump or tumor for testing. This type of biopsy can be done in a doctor’s office or clinic. It’s done with a thin, hollow needle much like those used for routine blood tests.

Your doctor may first numb the area over the tumor. The doctor then puts the needle right into the tumor and pulls cells and a few drops of fluid into a syringe. The sample is then sent to a lab, where it’s checked for cancer cells.

Doctors may use FNA biopsy if they are not sure whether a lump is a salivary gland cancer. The FNA biopsy might show the lump is caused by an infection, a benign (non-cancer) salivary tumor, or a salivary gland cancer. FNA biopsies are sometimes done on a lump in the salivary gland or on a suspicious lymph node in the neck. In some cases, this type of biopsy can help a person avoid unnecessary surgery.

An FNA biopsy is only helpful if enough cells are taken out to check. But sometimes not enough cells are removed, or the biopsy is read as negative (normal) even when the tumor is cancer. If the doctor is not sure about the FNA biopsy results, a different type of biopsy might be needed to get more cells and tissue.

Core needle biopsy

Sometimes, if the FNA biopsy is not able to get enough cells to test, the doctor might do a core needle biopsy that uses a hollow needle to take out pieces of tissue from a suspicious area. The needle may be attached to a spring-loaded tool that moves the needle in and out of the tissue quickly, or it may be attached to a suction device that helps pull tissue into the needle. Often an ultrasound is used to guide the needle.

A small cylinder (core) of tissue is taken out in the needle. Several cores are often removed and sent to the lab to be tested. 

Incisional biopsy

This type of biopsy may sometimes be done if the FNA biopsy didn't get a large enough sample. The biopsy can be done either in the doctor’s office or in the operating room, depending on where the tumor is and how easy it is to get a good tissue sample. In this procedure, the surgeon numbs the area over the tumor, makes a small incision (cut) with a scalpel (small knife) and takes out a tiny piece of the tumor. If the tumor is deep inside the mouth or throat, the biopsy might be done in the operating room while you are in a deep sleep under general anesthesia and then sent to the lab to be tested. These types of biopsies are not done often for salivary gland tumors.

Surgery

As mentioned above, FNA biopsy of a suspected salivary gland cancer may not always provide a clear answer. If this is the case but the physical exam and imaging tests suggest that it is cancer, the doctor may advise surgery to remove the tumor completely. This can give enough of a sample for a diagnosis and treat the tumor at the same time (see Surgery for Salivary Gland Cancer for more information).

In some cases, if the exams and tests suggest cancer, the doctor may skip the FNA biopsy altogether and go directly to surgery to remove the tumor. The entire tissue sample that is removed is then sent to the lab to confirm the diagnosis.

Lab tests on salivary gland biopsy samples

All biopsy samples are sent to a lab to be checked by a pathologist, a doctor who is specially trained to diagnose cancer from a biopsy. The doctor can usually tell cancer cells from normal cells, as well as what type of cancer it is, by the way the cells look. In some cases, the doctor may need to test the cells with special stains to help find out what type of salivary gland cancer it is.

For certain types of salivary gland cancers that have spread, molecular tests to look for certain proteins or genes changes might be done to help choose targeted drugs or immunotherapy drugs for treatment. For example:

• Androgen receptor: This is a protein on some salivary gland cancer cells that androgens (male hormones) bind to and help the cancer grow. Drugs that target these proteins and help slow the tumor growth are called anti-androgens.
• HER2: This is a protein on the outside of some salivary gland cancer cells that helps the cancer grow. These cancers are usually treated with drugs that target HER2.
• NTRK fusion gene: This is a gene change in one of the NTRK genes. Cells with these gene changes can lead to abnormal cell growth and cancer. There are targeted drugs available that go after cells with NTRK gene changes.
• Tumor mutational burden (TMB): TMB is a measure of the number of gene mutations (changes) inside the cancer cells. Cancer cells that have many gene mutations (a high TMB or TMB-H) might be more likely to be recognized as abnormal and attacked by the body’s immune system. If your cancer tissue is tested and found to have a high TMB (TMB-H), treatment with a certain immunotherapy drug might be an option.

Imaging tests for salivary gland cancer

Imaging tests use x-rays, magnetic fields, or radioactive particles to create pictures of the inside of your body. Imaging tests might be done for a number of reasons, before and after a cancer diagnosis, including:

• To help find a suspicious area that might be cancer
• To learn how far cancer may have spread
• To help find out if treatment has been effective
• To look for signs that the cancer has come back (recurred) after treatment.

X-rays

If you have a lump or swelling near your jaw, your doctor might order x-rays of your jaws and teeth to look for a tumor.

If you've been diagnosed with cancer, an x-ray of your chest might be done to see if the cancer has spread to your lungs. More often though, a CT scan of the lungs is done since they tend to give more detailed pictures.

Sometimes, panoramic dental x-rays might be done if radiation or certain types of surgery, like a mandibulectomy, are planned.

Computed tomography (CT or CAT) scan

A CT scan uses x-rays to make detailed cross-sectional images of your body. A CT scan can show the size, shape, and exact location of a tumor and can help find enlarged lymph nodes that might have cancer. CT scans can also be used to look for tumor spread in other parts of the body, like the lungs.

CT-guided needle biopsy: If a biopsy is needed of a certain area to check for cancer spread, a CT scan can be used to guide the biopsy needle into the mass (lump) to get a tissue sample to check for cancer.

Magnetic resonance imaging (MRI) scan

Like CT scans, MRI scans make detailed images of soft tissues in the body. But MRI scans use radio waves and strong magnets instead of x-rays. A contrast material called gadolinium is often injected into a vein before the scan to make pictures clearer.

MRI scans can help determine the exact location and extent of a tumor (for example, if it is growing into nearby tissues). If you have weakness or numbness of your face, an MRI scan can help see if any of the nearby nerves or muscles are affected by cancer or if the cancer is close to the skull bone. MRI scans are also helpful to look for cancer spread to the brain or spinal cord.

Positron emission tomography (PET) scan

For a PET scan, a slightly radioactive form of sugar (known as FDG) is injected into the blood and collects mainly in cancer cells.

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

PET/CT scans for salivary gland cancer might be done:

• If CT or MRI scans cannot find the main tumor
• To help plan surgery
• To help find the lymph nodes in the neck with cancer if radiation is the main treatment, instead of surgery.
• To look for cancer spread to distant parts of the body

Ultrasound

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. Ultrasounds can often be done of the major salivary glands and might be used to get a biopsy of a suspicious area. 

Neck ultrasound and biopsy: For this exam, a technician moves the transducer along the skin over your neck. This type of ultrasound can be used to look for lymph nodes in the neck to see if they are swollen or if they look abnormal inside which could be a sign of cancer spread. The ultrasound can also 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).

Quit smoking before treatment

It is very important to quit smoking  before any treatment for salivary gland cancer. If you quit smoking cigarettes before being diagnosed, it is important to not restart during treatment. Smoking during treatment can cause:

• Poor wound healing, especially after surgery
• More side effects from chemo
• Radiation to not work as well
• A higher chance of getting an infection
• Longer stays in the hospital
• A greater chance of dying 

Tests after salivary gland cancer is diagnosed

Other tests might be done as part of a work-up if a patient has been diagnosed with salivary gland cancer. These tests are not used to diagnose the cancer, but they may be done for other reasons, such as to see if a person is healthy enough for treatments such as surgery, radiation therapy, or chemotherapy.

Blood tests

No blood test can diagnose cancer in the salivary glands. Still, your doctor may order routine blood tests to get an idea of your overall health, especially before treatment. Such tests can help diagnose poor nutrition and low blood cell counts.

• A complete blood count (CBC) looks at whether your blood has normal amounts of different types of blood cells. For example, it can show if you are anemic (have a low number of red blood cells). 
• Blood chemistry tests can help determine how well your liver or kidneys are working. 

Heart and lung tests before surgery

If surgery is planned, you might also have an electrocardiogram (EKG) to make sure your heart is working well. Some people having surgery also may need breathing tests, called pulmonary (lung) function tests (PFTs).

Dental exam before radiation or surgery treatment

If radiation therapy or certain types of surgery (for example, removal of part of the jawbone) will be part of the treatment, you'll most likely be asked to see a dentist before starting. The dentist will help with routine dental care and dental x-rays, and may remove any bad teeth, if needed, before radiation treatment is started or surgery is done. Radiation can damage the saliva (spit) glands and cause dry mouth. This can increase the chance of cavities, infection, and breakdown of the jawbone.

Hearing tests

Cisplatin, a chemotherapy drug sometimes used to treat salivary gland cancer can cause hearing loss. You will most likely have your hearing checked (with an audiogram) before starting treatment to compare to later if you happen to have hearing problems from this chemo drug.

Nutrition and speech tests

Often, you will have a nutritionist who will evaluate your nutrition status before, during, and after your treatment to try and keep your weight and protein stores as normal as possible. You might also visit a speech therapist who will test your ability to swallow and speak. They might give you exercises to do during treatment to help strengthen the muscles in the head and neck area so you can eat and talk easily after treatment.