The tongue is actually a large muscle in the mouth that has two parts, the oral tongue is the part that is visible inside the mouth that is used to speak and eat, while the base of the tongue is farther back, and is part of the throat. When we talk about tongue cancer, we usually mean cancers of the oral tongue. However, for clarity it is often best to designate a lesion as arising either in the oral tongue or the base of tongue. Excessive tobacco and alcohol use are both known to contribute to the development of tongue cancer. Symptoms of tongue cancer include painful sores or ulcers that may bleed easily or make it difficult to speak. If a patient feels a new growth on their tongue, with or without these symptoms, it is a good idea for them to see a doctor to get it checked out. A biopsy may be necessary to determine if the growth is cancerous, and further evaluation with an MRI or a CT scan may be required. The treatment for tongue cancers is usually surgery, sometimes followed by radiation, and occasionally chemotherapy.
Read below to learn about Tongue Cancer:
Anatomy of Tongue Cancer
Tongue cancers are described by their location on the tongue, what other sub-sites they extend to (if any), how much of the tongue is involved, and how deeply they invade into the muscles of the tongue. Therefore, in order to begin to understand tongue cancer, it is important to first gain some background knowledge of tongue anatomy.
The tongue is a thick, muscular organ that consists of two main parts: the oral tongue and the base of tongue. These two parts are separated by the circumvallate papillae, which are dome-shaped projections on the surface of the tongue that house some of the taste buds of the tongue. When doctors talk about tongue cancers, they are usually referring to cancers of the oral tongue.
The oral tongue is the part that is visible when the mouth is open. It refers to the front two-thirds of the tongue, and is part of the oral cavity. The oral tongue is capable of moving in multiple directions and also plays a critical role in articulation (or speech). It also helps to manipulate food during chewing and to prepare the food to be moved to the oropharynx.
The oral tongue contains 4 different parts:
- Tip: this is the front part of the tongue.
- Lateral border: this is the side of the tongue, and there is one on the right and one on the left of the tongue.
- Dorsal surface: this is the top of the tongue, which is closest to the roof of the mouth.
- Ventral surface: this is the under surface of the tongue, which is connected to and closest to the floor of the mouth.
Base of Tongue
The base of tongue is actually part of the oropharynx, which is part of the throat, not the oral cavity. The base of tongue is not visible when the mouth is open, as it is located all the way at the back of the tongue.
The tongue is mostly muscle, but it is covered by a lining of mucosa. Most tongue cancers start in this mucosal lining. This lining is connected to the lining of other sub-sites of the oral cavity, particularly the floor of mouth, the retromolar trigone, and the anterior tonsillar pillar. Therefore, cancers that start in the tongue mucosal lining can easily extend to other sub-sites of the oral cavity.
The muscles of the tongue are divided into the extrinsic muscles and the intrinsic muscles:
- The extrinsic muscles begin somewhere outside of the tongue and end in the tongue, and are responsible for moving the tongue in different directions.
- The intrinsic muscles are located within the tongue, and are responsible for changing the shape of the tongue.
Causes of Tongue Cancer
Causes of Tongue Cancer
When a patient is diagnosed with cancer, it is common for them to wonder why. However, there is not always a clear answer to this question. Currently, there is no definitive cause of tongue cancer. It’s a combination of genetics and environmental factors. However, listed below are a few known risk factors for developing tongue cancer.
- Tobacco:This is by far the most common risk factor for tongue cancer. The use of cigarettes, cigars, pipes, or chewing tobacco substantially increases the chance of developing tongue cancer.
- Alcohol:Excessive alcohol consumption shows a strong association with the onset of oral squamous cell cancers. Moreover, smoking and drinking heavily more than doubles this cancer risk.
- Betel nut: The seed of the areca tree is often chewed by people from Southeast Asia and is known to cause tongue cancer.
- Viruses: The details of this are still being studied. Clearly, though, exposure to certain strains of Human Papilloma Virus (HPV) is associated with tongue cancer.
Other Factors Associated with Developing Tongue Cancer
- Marijuana use
- Poor dental hygiene
- Poor nutrition
- Genetic factors
Signs & Symptoms of Tongue Cancer
Signs & Symptoms
Unlike other cancers of the head and neck, tongue cancers can typically be seen or felt as an abnormality by a patient, dentist, or doctor. Symptoms to watch for include:
- Painful sores in the mouth: Most commonly, tongue cancer starts as a painful sore in the mouth that doesn’t heal after a few weeks.
- A patch on the tongue: Patches on the tongue are most commonly either red (erythroplakia) or white (leukoplakia). Red patches are more likely to be cancer than white patches; however, any patch in the mouth that is persistent for several weeks should be biopsied by a specialist.
- Difficulty speaking (dysarthria):This can occur when a tumour changes the way the tongue moves.
- Recurrent bleeding from the mouth: Growths in the mouth that are cancer tend to bleed easily when accidentally scraped while brushing teeth or eating certain foods.
- Bad breath: As cancers grow larger, dead cells within the tumour (necrotic cancer) lead to a bad smell from the mouth (halitosis).
In some cases, the first sign of tongue cancer could be a lump in the neck. This means that the tumour has spread to lymph nodes in the neck. However, in tongue cancers, the primary cancer in the mouth is usually noticed before it reaches these lymph nodes.
If tongue cancer grows to involve other parts of the oral cavity (such as the floor of mouth, alveolus, gums, jawbone and/or deeper muscles), the following symptoms might result:
- Loose teeth or dentures that don’t fit correctly: This occurs if the tumour invades the tooth sockets or the bones in which the teeth are rooted.
- Difficulty opening the mouth (trismus): This can happen if the cancer gets into any of the muscles that help to open and close the mouth.
- Numbness (i.e. in the lower teeth or lower lip/chin area): This means that the cancer cells have invaded the nerves that control the ability to feel.
- Pain or difficulty with swallowing: This can happen when tumours become large and get in the way of eating or involve the muscles and nerves of swallowing.
It is important to note that a patient could have one or more of these symptoms and not have tongue cancer. There are several non-cancerous causes of the same symptoms. That’s why it’s especially important to seek medical advice from a specialist.
Diagnosis of Tongue Cancer
The diagnosis phase of tongue cancer can be difficult and overwhelming. During this phase, further testing will be necessary to confirm a diagnosis and determine the best course of treatment. Patients can expect their doctor to have a discussion with them about the risks, benefits, and alternatives to each of the following approaches.
Because the tongue is readily accessible in the mouth, doctors may rely on a physical examination to establish an initial suspected diagnosis. More tests will follow, as described below.
Imaging scans, also known as radiologic studies, provide the doctor with an inside view of the body. Imaging of the head and neck will be required to determine the extent as well as the behaviour of a growth, and may be required prior to treatment of a tumour in the tongue. The most common initial imaging tests used are CT and MRI scans. A more advanced imaging study called a PET/CT will likely also be performed to evaluate if the cancer has spread to other sites in the body as well as to determine if lymph nodes in the neck are likely to harbour cancer cells.
A biopsy is the removal of a small piece of tissue to examine under a microscope to see if it is cancerous. A biopsy of a suspicious area in the mouth (or mass in the neck) is usually needed prior to treatment. There are a few different ways to perform this biopsy, but the most common and easiest approach is an incision or punch biopsy. In some cases, a fine needle aspiration (FNA) biopsy of any suspicious lymph nodes in the neck may also be helpful.
Type of Tongue Cancer
After diagnosing a patient with tongue cancer, a doctor will need to determine what type of cancer it is, the grade of the tumour, and the stage of the cancer. Doctors often establish a preliminary disease stage based on physical exam as well as findings on imaging that help to identify the spread of disease. In patients who undergo surgery, a more well-defined disease stage is determined based on pathology after surgery. It is important to note that oral cancers can sometimes be difficult to diagnose. If a doctor is having a hard time determining what type of cancer it is, he or she might ask for a second opinion and send some pieces of the tumour off to a specialist in head and neck pathology who deals more frequently with these types of tumours.
The most common type of tongue cancer is squamous cell carcinoma. More than 90% of mouth cancers are squamous cell carcinoma. Squamous cell carcinoma is a cancer that starts from abnormal cells on the surface layer of the lips or the lining of the mouth. If the cancer is discovered at an early stage, before invading past the deepest layer of the mouth lining, then it is called carcinoma in situ and has a good prognosis when removed. Another subtype is called verrucous carcinoma. This sub-type usually has a slow growth pattern and is less likely to spread to lymph nodes in the neck or other parts of the body.
Less common types of tongue cancer
|Carcinoma in situ (also called severe dysplasia)||This cancer is an early stage of squamous cell carcinoma in which there are cancerous cells on the lining of the mouth but they have not invaded past the outermost layer of tissue.|
|Verrucous carcinoma||This is a type of squamous cell carcinoma that has a better prognosis because it is less likely to spread.|
|Salivary gland cancers||There are minor salivary glands located under the lining of the mouth. This is why cancers in this region can be glandular malignancies referred to as adenocarcinomas, including mucoepidermoid carcinomas, and adenoid cystic carcinomas.|
|Lymphoma||The mouth also has lymphoid cells under the surface. This is why lymphoma could in rare cases appear as a lump in the mouth.|
|Mucosal melanoma||These cancers come from skin cells (melanocytes). In rare cases, melanoma can be found in the lining of the mouth, nose and/or throat.|
Grade of Tongue Cancer
A doctor will rely on final pathology of the tumour to determine the grade and stage of the cancer. The grade is usually only determined after the tumour has been removed. The grade of cancer relates to how healthy or unhealthy cells look under a microscope. In other words, a pathologist will determine the grade of cancer by comparing the amount of the healthy-looking tissue to the amount of cancerous tissue. If most of the tumour cells look like normal tissue then the cancer is “well differentiated” or “low-grade.” However, if the tumour cells look very different from normal tissue then the cancer is “poorly differentiated” or “high-grade.” The grade of cancer may help to determine how quickly the cancer is likely to spread.
Oral cancer grading is described as the following:
|GX||The grade cannot be evaluated.|
|G1||The cells look more like normal tissue and are well differentiated.|
|G2||The cells are only moderately differentiated.|
|G3 and G4||The cells don’t look like normal tissue and are poorly differentiated.|
Stage of Tongue Cancer
The stage of a cancer is determined by the TNM staging system:
- The ‘T’ stands for tumour size.
- The ‘N’ stands for lymph node involvement.
- The ‘M’ stands for distant metastases, or cancer spread to other areas of the body.
Staging helps doctors determine how serious the cancer is and how best to treat it. Staging systems often reference very specific anatomical structures. Please reference the anatomy page to learn more about these terms.
Staging is generally based on the American Joint Committee on Cancer (AJCC) 8th edition guidelines. To learn more, see the AJCC TNM Staging Table and the TNM Staging Tool below.
TNM Staging Table, from the American Joint Committee on Cancer (AJCC)
|Any T||Any N||M1||IVC|
American Joint Committee on Cancer, 8th Ed. 2017
Treatment Plan for Tongue Cancer
After determining a diagnosis and completing a full pre-treatment evaluation, doctors will recommend a course of treatment for their patients. This treatment plan will depend on whether or not the cancer has spread to other regions. In general, there are three different options for the treatment of tongue cancers that can be used alone or in combination.
For tongue cancer, complete surgical removal of the tumour is almost always the first treatment, unless a doctor decides that it is not possible or safe to proceed with surgery. Tongue cancers are commonly treated with a type of surgery called a glossectomy.
The surgery that a doctor recommends will depend on the location of the cancer, as well as the stage. The extent and location of a tongue resection will determine the type of reconstruction required and will also allow the doctor to predict the impact that it will have on speech and swallowing. Patients and their care teams should discuss the types of surgeries that may be required for the treatment of their cancer.
The most common use of radiation for the treatment of tongue cancer is called adjuvant radiation, which is radiation given after surgery in order to decrease the chances that the tumour will come back.
Reasons for Post-Surgical Radiation
A doctor may recommend post-surgical radiation in a few scenarios.
- If the tumour was not completely removed or if the surgical margins were positive for cancer.
- If the type of cancer was determined to be aggressive or of a high grade or T-stage.
- If the cancer had spread to lymph nodes or other structures, such as nerves or vessels.
In some cases, complete surgical removal of a tongue cancer may be impossible or unsafe, and a doctor may recommend radiation therapy as the primary treatment. In this type of treatment, an external beam of radiation is directed at the tumour in order to destroy the rapidly dividing cancer cells.
Chemotherapy is not commonly used to treat tongue cancer. In some cases, it is used in combination with radiation as additional treatment following surgery. Chemotherapy is usually only added to adjuvant radiation therapy if there is extranodal extension from cancerous lymph nodes in the neck, or if there is cancer left behind during surgery.
General Treatment Options for Tongue Cancer
These options depend on T and N stages.
- The preferred treatment is surgical removal of the cancer, with or without a neck dissection, depending on the location of the tumour and on how thick the tumour is.
- A sentinel lymph node biopsy (a procedure to remove and examine the sentinel lymph nodes, which are the first lymph nodes to which cancer cells are likely to spread) may also be performed, and may be followed by a neck dissection, depending on the results of the biopsy.
- Surgery will sometimes be followed by radiation, additional surgeries, and/or chemotherapy with radiation, depending on the outcome of the primary surgery.
- Radiation alone is also a primary treatment option.
- Radiation could be followed by surgery, depending on whether any disease remained after the initial radiation.
T3, N0; T1-3, N1-3; or T4a, any N
- The initial treatment is surgical removal of the cancer with neck dissection(s).
- Surgery will sometimes be followed by radiation, additional surgeries, and/or chemotherapy with radiation, depending on the outcome of the primary surgery.
- Factors that will guide additional treatment include:
- Positive margins (the presence of cancer cells at the edge of the tissue that was resected).
- Spread of cancer beyond the lymph nodes in the neck (extranodal extension).
- T3 or T4 tumours based on pathological evaluation.
- N2 or N3 disease in the neck lymph nodes.
- Cancerous lymph nodes in unusual parts of the neck.
- Tumour invasion into or around nerves (perineural invasion).
- Tumour invasion into blood vessels (lympho-vascular invasion).
T4b, any N; unresectable neck disease; or patients unfit for surgery
In cases that are very advanced, or in patients who are extremely sick, patients should have an extensive discussion with their doctor in order to consider the possibility of palliative therapy or hospice care.
Prognosis of Tongue Cancer
A prognosis is a prediction of the outcome of one’s disease. How likely is survival? Will the cancer come back? These are the big questions on most people’s minds after receiving a diagnosis of tongue cancer. In general, there are several characteristics of the tumour that can inform a patient about their chances of being cured.
Factors That Affect Prognosis
This is the most important factor that affects a patient’s chance of being cured.
The location of the tumour in the oral cavity can affect the surgeon’s ability to resect the tumour with adequate margins of healthy tissue around it.
Type and Grade
Both the type and grade of the tumour determine the amount of treatment necessary and the ultimate prognosis.
Spread to Lymph Nodes
This helps determine stage, but even without other factors, spread to lymph nodes in the neck decrease the chance of cure, especially if there is evidence of growth of cancer outside of the lymph node.
The ability to completely remove the tumour with a margin of normal tissue around it can be a very important factor in a patient’s prognosis.
Spread into Local Structures
Spread into large nerves, skin, and bone has been shown to indicate a worse prognosis.
While each of these factors contributes to one’s outcome, patients should have a discussion with their doctor to determine their overall prognosis. Giving a percentage of survival is challenging because cancer research often looks at multiple types of cancer and may include a large range of patients who underwent a variety of treatments.
What to Expect After Tongue Cancer Treatment
What to Expect After Treatment
After treatment, patients should follow-up with their doctors on a regular basis.
Patients should visit their head and neck specialist on a regular schedule (or earlier if they have any concerning symptoms). This allows doctors to monitor the patient for any sign that the cancer has returned. The best timeline for follow-up will be determined by the doctor.
Standard Follow-up Schedule
- For the first year, go every 1-3 months.
- For the second year, go every 2-6 months.
- For the third to fifth year, go every 4-8 months.
- After five years, start going once annually.
Doctors may select a scan to be performed in the first 6 months after treatment. The first scan serves as a “baseline” study for the purpose of comparing future studies. This will depend on the type and location of the cancer. Imaging could range from something as simple as a quick chest X-ray to more extensive tests such as a CT, MRI, or PET scan. If something suspicious comes up, a patient may need a biopsy.