Floor of the mouth cancer is cancer that starts as a growth of cells under the tongue.

Floor of the mouth cancer most often begins in the thin, flat cells that line the inside of the mouth, called squamous cells. When cancer starts in these cells it's called squamous cell carcinoma.

Floor of the mouth cancer causes changes in the look and feel of the tissue under the tongue. These changes may include a lump or a sore that doesn't heal.

Floor of the mouth cancer treatments include surgery, radiation therapy and chemotherapy.


Symptoms of floor of the mouth cancer can include:

  • Mouth pain.
  • Sores in the mouth that won't heal.
  • Trouble moving the tongue.
  • Loose teeth.
  • Pain with swallowing.
  • Weight loss.
  • Ear pain.
  • Swelling in the neck that may hurt.
  • White patches in the mouth that won't go away.

When to see a doctor

Make an appointment with a doctor or other health care professional if you have any symptoms that worry you.

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Floor of the mouth cancer happens when cells under the tongue develop changes in their DNA. A cell's DNA holds the instructions that tell a cell what to do. In healthy cells, the DNA gives instructions to grow and multiply at a set rate. The instructions also tell the cells to die at a set time. In cancer cells, the DNA changes give different instructions. The changes tell the cancer cells to make many more cells quickly. Cancer cells can keep living when healthy cells would die. This causes too many cells.

The cancer cells might form a mass called a tumor. The tumor can grow to invade and destroy healthy body tissue. In time, cancer cells can break away and spread to other parts of the body. When cancer spreads, it's called metastatic cancer.

Risk factors

The most common factors that can increase the risk of floor of the mouth cancer include:

  • Using tobacco. All forms of tobacco increase the risk of floor of the mouth cancer. This includes cigarettes, cigars, pipes, chewing tobacco and snuff.
  • Drinking alcohol. Frequent and heavy drinking increases the risk of floor of the mouth cancer. Using alcohol and tobacco together increases the risk even more.
  • Being exposed to human papillomavirus. Human papillomavirus, also called HPV, is a common virus that's passed through sexual contact. For most people, it causes no problems and goes away on its own. For others, it causes changes in cells that can lead to many types of cancer.
  • Having a weak immune system. If the body's germ-fighting immune system is weakened by medicines or illness, there might be a higher risk of floor of the mouth cancer. People with a weakened immune system include those taking medicines to control the immune system, such as after an organ transplant. Certain medical conditions, such as infection with HIV, also can weaken the immune system.


To lower the risk of floor of the mouth cancer:

  • Don't use tobacco. If you don't use tobacco, don't start. If you currently use tobacco of any kind, talk with a health care professional about strategies to help you quit.
  • Limit alcohol intake. If you choose to drink alcohol, do so in moderation. For healthy adults, that means up to one drink a day for women and up to two drinks a day for men.
  • Ask about the HPV vaccine. Receiving a vaccination to prevent HPV infection may reduce your risk of HPV-related cancers. Ask your doctor or other health care professional whether an HPV vaccine is right for you.
  • Have regular health and dental exams. During your appointments, your dentist, doctor or other health care professional can check your mouth for signs of cancer and precancerous changes.

Floor of the mouth cancer care at Mayo Clinic

Oct. 14, 2023

Living with floor of the mouth cancer?

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