Diagnosing Tongue Base Cancer
Getting to a diagnosis begins with a history and physical examination. If the symptoms haven’t been present for very long, or if the history and physical examination make the doctor less suspicious that your lesion is cancer, your doctor might try some medications and rehabilitation before jumping to a diagnosis of cancer.

At some point, if your doctor is not certain of a diagnosis, and if symptoms aren’t getting better (and if symptoms are getting worse), your doctor should raise the possibility of starting a cancer work-up. Like most cancers in the head and neck, this will include some combination of biopsy and imaging tests.

Be sure to bring all reports and images from any prior treatment with you to your appointment with your head and neck cancer specialist.

Imaging refers to radiologic studies, or scans, that create pictures of the structures inside your head and neck. In general, for small tumours that are easily evaluated on physical examination, imaging might not be necessary. For larger tumours, or tumours in locations that are difficult to examine, your doctor will probably order some sort of imaging to get more information about the tumour location and possible spread to regional lymph nodes.

The two main imaging techniques used are computed tomography (CT) scans and magnetic resonance imaging (MRI) scans. Ultrasound is a quick and inexpensive way to get information about disease that is in lymph nodes in the neck. PET scans are studies that look at the function of cells in the body, and they are being used more and more in oncology. PET scans can be combined with other imaging methods such as CT scans to get more detailed information.

CT Scan: This is a quick series of X-rays that can show very good detail of the anatomy. It is helpful in seeing the extent of the main tumour mass and what structures it has invaded. It can also help detect spread into the neck.
 Advantages: A CT scan is a quick test that is readily available and gives a great deal of useful information.
 Disadvantages: A CT scan involves radiation, and the images can be degraded by movement and dental work. It only shows late changes associated with invasion into nerves (such as destruction of the bone where the nerve enters the skull).
 Important points: A CT scan looking for throat tumours should be done with a contrast dye that is injected into your veins, unless there is some reason that you cannot receive contrast. Allergies to iodine and shellfish are common indications that a patient may be allergic to contrast dye.
 What to expect: First, a nurse will insert an intravenous line into a vein to allow for contrast injection. Then you will have to lie flat on a table with your head in a little holster to help keep it totally still. CT scans are typically open, so you shouldn’t feel enclosed. You will then get an injection of contrast, and soon after, the scanner will start moving and taking pictures; this part should only take one or two minutes. Try not to swallow, speak or move during this quick test.

MRI: This test uses magnets to create a picture of the inside of the neck. It is good for showing more subtle details of how extensive the main tumour mass is. It can also help pick up spread of cancer to lymph nodes in the neck.
 Advantages: There is no radiation involved, and the details of the soft tissues are better than that of a CT scan.
 Disadvantages: An MRI takes much longer than a CT scan and is more expensive. Some people feel enclosed inside the MRI machine and may require sedation to get through the study.
 Important points: This test should be done with and without contrast injected into your veins, unless there is some reason you can’t have contrast. Closed MRI machines usually give better pictures than open MRI machines.
 What to expect: First, a nurse will insert an intravenous line into a vein to allow for contrast injection. Then you will have to lie flat on a table with your head in a little holster to help keep it totally still. Due to the strength of the magnets, you will be instructed to remove any metallic objects and to change into a hospital gown before entering the room where the scanner is located. You will then enter the scanner, and the MRI machine will start moving and taking pictures. This can take 30 to 60 minutes, depending on how the scan is done. Try to stay as still as possible throughout the test.

Positron Emission Tomography (PET): Doctors are still studying the most appropriate uses of PET scans for head and neck cancer. The main uses of PET scans at this point are to see if there is spread to sites in the neck or other parts of the body or to help find a primary tumour when the only evidence of cancer is a lymph node that has cancer in it. It is often combined with a CT scan (or in some cases an MRI) to help pinpoint the location of active cells.

Neck ultrasound: An ultrasound is a way to look at vessels, structures and lymph nodes all over the body, particularly in the neck and thyroid gland. You are not exposed to any radiation, and it doesn’t hurt. Basically, a technician or a radiologist will place some cold jelly over the area that is being examined and rub a plastic probe over the area to take pictures. The technician can see enlarged lymph nodes and nodules deep in the neck and describe details about them such as whether they have fluid inside, have a lot of blood vessels around and so on. While the ultrasound is being performed, a doctor can place a needle into a lymph node or nodule and draw off cells (this is an ultrasound-guided biopsy).

Chest X-ray: This is a quick, inexpensive and easy way to look for signs of spread of cancer into the lungs or the possibility of a different cancer in the lungs. Some doctors will recommend a chest X-ray every year as follow-up if you have had a head and neck cancer. This is because patients who have had head and neck cancer are at a higher risk of getting lung cancer as well.

A biopsy is the removal of a small piece of tissue to examine under a microscope to see if it is cancerous. At some point, you will need a biopsy of the suspicious lesion in your throat. The biopsy report is extremely important for determining your diagnosis and treatment plan.
When performing a biopsy on a neck mass, your doctors should test for certain viruses such as human papillomavirus (HPV) and Epstein-Barr Virus (EBV). They can also test for proteins related to these viruses (e.g. P16 as it relates to HPV infection). Cancerous lymph nodes that have the HPV virus (or P16 protein) are very likely to be related to a primary cancer in the oropharynx. A positive HPV or P16 test should make your doctor spend extra time and effort looking for a small or hidden tumour somewhere in the oropharynx.
Biopsy of base of tongue lesions
Typically, you will undergo endoscopy with biopsy. Exactly how the endoscopy is done will be up to your physician. The three general ways to biopsy a suspicious area in the oropharynx are:

Transnasal flexible endoscopy with biopsy: If your doctor sees a suspicious lesion that he or she might be able to biopsy in the office, this method is a possibility. This is just like having a transnasal flexible laryngoscopy, except the camera used in this case has a special attachment through which your doctor can spray medicine directly onto the area of interest to numb it. Through that same attachment, your doctor can pass a thin biopsy forceps and clip off a tiny piece of the suspicious growth.

The main advantage of transnasal flexible endoscopy with biopsy is that it is usually quick and easy, and you don’t need to go to an operating room or go under general anaesthesia. However, your doctor can only get a tiny piece of tissue this way, and it might not lead to the correct diagnosis. Also, it’s not as good a view as a direct examination in the operating room. Finally, your doctor can’t feel around or get as good a look as with a direct laryngoscopy.

Direct laryngoscopy with biopsy: Your doctor might choose this technique if he or she can’t get a good biopsy in the office or wants to get a better look all around your throat in the operating room.
For the base of tongue, your doctor might either take a small piece in the operating room to confirm the diagnosis, or he or she might remove a large piece of the base of tongue (sometimes using tools like lasers and robots to help) to try to remove the entire tumour. Also, your surgeon will take the opportunity to thoroughly feel all around your neck, mouth and throat while you are asleep. Finally, he or she will look for any additional suspicious lesions (called second primaries). One of the other advantages of this technique is that frozen section pathology is usually available in the operating room to make certain that enough tissue has been sampled in order to make a definitive diagnosis.
For this to be done, you will go to sleep with anaesthesia in an operating room with a small breathing tube placed through your mouth into your windpipe. Then your surgeon will place an instrument called a laryngoscope through your mouth and look all over your throat. He or she can even use a longer scope, called an esophagoscope, to look at the upper part of your esophagus. The surgeon will then use small forceps to take a piece of tissue from any suspicious looking area. In some cases, the doctor might remove the entire lesion, for which he or she may use a variety of different instruments, including a laser.

If needed, your doctor might talk to you in advance about doing a tracheotomy or a feeding tube during this procedure while you are asleep.

Biopsy of neck masses
If there is also a lump in the neck, your doctor might decide to biopsy that as well. There are a few different ways to do a biopsy of the neck.

Fine needle aspiration biopsy: The most common and easiest way to biopsy is fine needle aspiration biopsy (FNAB), in which a tiny needle is placed into the tumour and some cells are drawn out through a syringe. The pathology doctor, known as a cytologist or cytopathologist, will then immediately look at the cells under the microscope and let your doctor know if there were enough cells to make a diagnosis. Several “passes” might be done to increase the likelihood that there are enough cells to make a diagnosis. The final diagnosis may take a few days to come back, so be patient.

Core biopsy: Core biopsy is an alternative to fine needle aspiration. A core biopsy is done in the same way as an FNA biopsy, but it uses a larger needle and removes a core of tissue from the tumour rather than just a few cells. The likelihood of false positives and false negatives is much lower with a core needle biopsy than with a fine needle biopsy.

Open neck biopsy: An open biopsy involves making an incision over the tumour and removing a piece or all of the tumour to make a diagnosis. An open biopsy of a neck mass is performed through an incision over the lump, and either a piece (incisional open neck biopsy) or the entire lump (excisional open neck biopsy) is removed to make a diagnosis. Except in a few special circumstances (such as if the tumour is likely a lymphoma or if other methods of diagnosis have not worked), this method should not be used to find the diagnosis of a neck mass.