Cancer of the Floor of the Mouth

Cancer of the floor of the mouth occurs when a group of cells under your tongue become abnormal and start to grow out of control. Most of the time, this type of cancer starts in very thin, flat cells (squamous cells) that cover the surface of your mouth. Cancer cells can spread and form a mass of cells called a tumor. The cancer may spread deeper into the floor of the mouth, or it may spread to other areas of the body (metastasize).


The exact cause of cancer of the floor of the mouth is not known. However, some risk factors make this more likely:

  • Use of tobacco products, including cigarettes, pipes, cigars, smokeless (chewing) tobacco, and snuff. This is the number one risk factor for cancer of the floor of the mouth.

  • Male gender.

  • Age of 50 years or older.

  • Poor oral hygiene (not brushing your teeth or flossing regularly).

  • Frequent use of alcohol.

  • Human papillomavirus (HPV) infection.


  • An open sore (ulcer) on the floor of your mouth, which does not heal. The sore usually does not hurt.

  • A white or red patch on the floor of your mouth. This might show up before an ulcer appears, or it might be next to an ulcer.

  • A lump on the floor of your mouth.

  • Pain in your mouth.

  • Pain in your ear.

  • Bad breath.

  • Loose teeth, dentures that no longer fit, or dentures that are painful to put in or remove.

  • Bleeding in your mouth.

  • Pain in your jaw.

  • Numbness in your mouth or on your chin.

  • A lump on your neck.


To diagnose cancer of the floor of the mouth, your caregiver may perform the following exams: 

  • A physical exam of your mouth, throat, and neck for a sore or lump. Your caregiver will use a finger from one hand to feel the floor of your mouth and use the other hand to press firmly under your jaw.

  • Removal and exam of a small number of cells (biopsy) from your mouth or a lump in your neck. These cells are checked under a microscope for cancerous formations.

  • Imaging exams, such as X-rays of your mouth and neck. The images can show if there is an abnormal mass.

If you do have cancer, your caregiver will stage your cancer. Staging provides an idea of how advanced your cancer is. The stage of your cancer will depend on how much it has grown and if it has metastasized. The meaning of the stage depends on the type of cancer. For cancer of the floor of the mouth:

  • Stage I means the cancer is the size of a peanut or smaller. It has not metastasized.

  • Stage II means the cancer is larger than a peanut, but not larger than a walnut. It has not metastasized.

  • Stage III means the cancer has grown larger than a walnut. It may have spread to a lymph node or lymph gland on the same side of your neck as the cancer. (Lymph is a fluid that carries white blood cells all over your body. White blood cells fight infection.)

  • Stage IV means the cancer has spread to nearby areas. It may have spread heavily into your lymph glands.


Treatment for floor of the mouth cancer can vary. It will depend on the stage of your cancer and your overall health. Treatment options may include:

  • Radiation therapy. This uses waves of nuclear energy to kill cancer cells. It may be used as the only treatment for stage I or stage II cancers.

  • Surgery to remove the cancer cells. Surgery done for stage I and stage II cancers will not change your speech or swallowing very much. Surgery for stage III and IV cancers will permanently change the appearance of your mouth as well as your swallowing and speech.

  • A combination of radiation, surgery, and drugs that kill cancer cells (chemotherapy). This may be needed for stage III and stage IV cancers.

Additional surgery may be needed if the cancer has spread to your lymph nodes or jawbone. You may also need surgery to make it easier for you to swallow and talk.


  • You have pain in your mouth or ear.

  • Your mouth or chin is numb.

  • The way you speak changes.

  • The way you swallow changes.


  • Your pain gets worse. The pain may be in your mouth or your ear.

  • You have bleeding in your mouth.

  • Your mouth or neck swells.

  • You have difficulty swallowing.

  • Your lower teeth become loose or painful.

  • You have difficulty breathing.

  • You have a fever.