• Floor of Mouth Cancer
  • Symptoms and Diagnosis
  • Staging
  • Treatment

Floor of Mouth Cancer

The floor of the mouth contains some very important structures: the submandibular & sublingual saliva gland, their ducts, the nerves of movement, sensation & taste to the tongue (Fig. 1 Floor of Mouth). Additionally, the tumors of the floor of mouth are adjacent to the jawbone and can easily invade and get inside the bone.

The floor of mouth is divided in the center in two halves. This is also an important division because the tumors that are limited to one side tend to only involve the lymph nodes on the same side of the neck while the tumors that cross this barrier may have involvement of lymph nodes on both sides (most tumors however, involve both sides).

As mentioned before, most cancers of the mouth arise from the mucosal covering and not from the tissue underneath it, and they are called Squamous Cell Cancer (SCCA).

This is presumably because the mucosa that is covering is exposed to the environment and what enters our mouths that can cause cancer, while the tissue underneath does not get the same kind of exposure. However cancers of the mucosa of the mouth very easily grow into the underlying tissue because the mucosa is thin.

Risk Factors

Men are more often affected by cancer of the oral cavity than women. Cancer of the mouth is closely associated with cigarette smoking. Exposure to the chemicals in tobacco as they pass by the structures in the mouth, throat, voice box, and lungs is thought to lead to development of cancer.

Tobacco and alcohol use each have been found to increase the risk by many folds (as high 20-30 folds). However, tobacco and alcohol use together can increase the risk of cancer by 70 folds. There is also an association with HPV (human papilloma virus) infection.

Symptoms and Diagnosis

Mouth cancer usually occurs in stages, by that I mean the tumor will usually first start as a small white or red discoloration on the surface. White lesions are called leukoplakia, and red lesions are called erythroplakia. These lesions can be at first not cancerous but be in the process of developing into a cancer. The red lesions have a much greater probability of becoming cancerous, however both white and red lesions have an unacceptably high risk and are worrisome; they need to be evaluated by a physician immediately.

Often times if the lesion looks suspicious to your physician a biopsy will be performed (removal of a very small portion to look under the microscope). If a lesion is noted to change shape and size it must be biopsied immediately.

In the early stages of cancer the lesion often looks like a harmless sore. Sometimes these sores are painful, but often they cause no discomfort at all. Other symptoms may include bleeding, pain when chewing, and at times ear pain that is mild but persistent on the same side as the tumor. (Fig. 2 Floor of Mouth Cancer)

It is important to see a physician if one notices any changes or new growths in the mouth. Regular visits to a dentist are important as well, as he or she will be sure to notice any suspicious changes. A biopsy is the only definitive test to diagnose cancer; no treatment can be started without a diagnosis.

In addition, diagnostic imaging may be required as well, such as a CAT Scan or MRI to check to see how deep into the deeper tissue or jaw bone the cancer has grown (this may not be visible to the eye), as well as looking at the lymph nodes in the neck. (Fig. 3 CT) With larger tumors a PET Scan should be done as well to see whether the cancer has spread to the lymph nodes or other parts of the body. Fig. 4 PET/CT Scan- (a.) CT Scan (b.) PET Scan (c.) Fusion of the two Scans.

a. CT Scan

b. PET Scan

c. Fusion of the two Scans


The TNM Staging is a universally used system based on size of the original tumor and involvement of the tissue next to it (T), the size and extent of lymph node involvement (N), and distant spread to other parts of the body or metastasis (M). The same staging system is used for all oral cavity cancers.

Table 1
T Stage Primary Tumor
Tx Primary Tumor Cannot be Assessed
Tis Carcinoma in situ
T1 Tumor 2cm or less
T2 2 to 4 cm
T3 Greater than 4cm
T4a Tumor Invades Adjacent Structures
T4b Invades Masticator Space,Pterygoid Plates Skull Base or Encases Carotid Artery
N Stage Regional Lymph Nodes
Nx Node Cannot be Assessed
N0 No Lymph Nodes
N1 Single Node Less than 3cm on the same side
N2a Single Node 3 to 6 cm on the same side
N2b Multiple Nodes Less than 6cm on the same side
N2c Nodes on Both or Other Side Less than 6cm
N3 Node Larger than 6cm
Distant Metastasis
Mx Distant Metastasis Cannot be Assessed
M0 No Distant Metastasis
M1 Distant Metastasis Present
Table 2
Stage Group
Stage T N M
0 Tis N0 M0
I T1 N0 M0
II T2 N0 M0
IVa T4a
T1,T2,T3 or T4a
Any T
Any N
IVc Any T Any N M1


The choice of treatment for floor of mouth cancers is dependent on the stage, and more specifically the size, location, and the spread of tumor. Floor of mouth cancers can be very misleading, and could be more aggressive than they appear. They can easily involve the deep tissue including the saliva glands, nerves and the jaw bone. Most tumors require two modes of therapy and in the very advanced tumors even three modes of therapy. The three available therapies (modes of therapy) are surgery, radiation therapy, and chemotherapy.

This is a very complex subject, but we will try to simplify it here as much as possible by stating some simple facts: First, chemotherapy alone cannot cure squamous cell cancer; chemotherapy is given in combination with radiation therapy, and in doing so it makes the radiation therapy more effective. Second, radiation alone and surgery alone can only be used for the very small lesions that have not shown signs of spread. Third, if possible surgery should be used as one of the modes of therapy as improves the cure rate to a great degree. Patients who have surgery will continue to speak and eat normally if the procedure is done by expert head & neck cancer surgeons and reconstructed appropriately.

Floor of mouth cancers in a majority of cases are curable and there is great hope. At the center we see patients with mouth cancer frequently. This is a very aggressive and potentially deadly cancer; do not take this tumor lightly. In cases of small tumors a simple surgery alone will be enough. When the tumors are larger the concern becomes involvement of deeper structures, and specifically the nerves. We have many saliva glands that can compensate for the removed floor of mouth glands, but saving the nerves is a priority during surgery (if possible). Additionally, if the bone is involved a portion of the bone may need to be also removed (every attempt will be made to preserve as much of the bone as possible). A neck dissection to remove the lymph nodes in the neck is an important part of treatment as they may be hiding cancer cells. In the larger tumors, most common and effective mode of therapy is surgery followed by radiation therapy. In the more advanced cases, surgery is followed by both chemotherapy and radiation.

Chemotherapy and radiation alone are only used for patients that cannot have surgery either because of health reasons or if the tumor is too large to remove. Our team of doctors evaluates each case thoroughly, a patient is seen by a head & neck surgeon as well as reconstructive surgeon, to plan an appropriate surgical plan. Surgical expertise is extremely important in both improving cure rates and speech and swallowing function. We will work with your oncologist and radiation oncologists or if you don’t have these physicians we will make such a team of doctors for you. Bear in mind, this tumor is extremely aggressive and time is of the essence. Before treatment begins all patients will need to be seen by their dentist in preparation for their course of therapy. After surgery therapy to resume speech and swallowing, if needed, will begin right away. Our speech and swallowing outcomes are excellent. The most important aspect of therapy is having an experienced team that you trust.