Oral cancer involves malignant growths or tumors that can occur anywhere in the mouth or the throat. Doctors sometimes recommend radiation therapy to treat it, which involves doses of radiation to destroy cancerous cells.

According to older research from 2010, the early detection of oral cancers can be one of the most effective ways to help ensure successful treatment, reducing death and disfigurement.

Treatment usually involves a combination of surgery, which removes cancer cells, and radiation therapy, also called radiotherapy.

Doctors will diagnose around 53,000 new cases of oral cancer in the United States annually, accounting for roughly 3% of all cancers diagnoses.

This article will explain how radiation therapy works for oral cancer, including its benefits, side effects, and types.

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Radiation therapy involves high doses of radiation particles or X-rays to kill cancer cells or slow their growth. These high doses damage the DNA of the cancer cells, meaning they can no longer divide and spread. Once they die, the body breaks them down and removes them.

The American Cancer Society (ACS) says doctors can use radiation therapy in combination with other forms of treatment, such as:

  • following surgery to destroy any cancer cells that may remain
  • before surgery to shrink the larger cancer cells
  • alongside chemotherapy treatment
  • with targeted cancer medications

Radiation therapy might not yield results instantly. It may take days or weeks to cause enough damage to the DNA of the cancer cells that will lead to their death.

However, applying radiation to these parts of the body can lead to issues for the teeth, gums, and throat. The ACS recommends speaking with a dentist to ensure the mouth is healthy before treatment. They also suggest quitting smoking beforehand, if applicable, as it can cause a negative response to treatment.

Read more about radiation therapy.

What is oral cancer?

Oral cancer involves cancers of the oral cavity and oropharynx, which is the part of the throat toward the back of the mouth.

The oral cavity includes the:

  • teeth
  • lining of the cheeks and lips
  • lips
  • gums
  • floor of the mouth below the tongue
  • area behind the wisdom teeth
  • bony roof of the mouth
  • front two-thirds of the tongue

The oropharynx lies behind the oral cavity. It includes the:

  • soft palate
  • base of the tongue
  • side and back walls of the throat
  • tonsils

The most common causes of oral cancer occur due to infection by the human papillomavirus or tobacco and alcohol use.

Symptoms of oral cancer include:

  • sores, lumps, or irritating patches in the mouth, on the lip, or in the throat
  • discolored patches in the mouth
  • issues with chewing, swallowing, or talking
  • swelling around the jaw
  • issues when moving the tongue or jaw
  • numbness in the area

Read more about the warning signs of oral cancer.

The use of radiation therapy to treat oral cancer has several benefits, including:

  • destroying cancer cells
  • preventing the cancer from returning
  • shrinking larger cancers
  • easing symptoms of advanced cancer, such as pain, bleeding, or trouble swallowing

Radiation therapy and techniques doctors use to destroy cancer cells can also kill nearby healthy cells. This can result in some long lasting or permanent side effects.

A few of these include:

  • Dry mouth: Radiation can cause damage to the salivary glands, resulting in a dry mouth.
  • Difficulty swallowing: Radiation to the throat and oral cavity can lead to painful sores, which make drinking and swallowing difficult.
  • Thyroid issues: Radiation can damage the thyroid gland, which can alter the levels of thyroid hormones in the body.
  • Damage to the jaw bone: Radiation can lead to a serious condition known as osteoradionecrosis of the jaw.
  • Damage to the carotid artery: Radiation to the neck area can damage the carotid artery, increasing the risk of stroke.
  • Lymphedema: Radiation therapy can result in swelling of the head and neck regions, known as lymphedema.
  • Skin problems: Radiation therapy can cause the skin within the treatment area to turn red or darker. A person may also experience soreness.

Read more about the side effects of radiation therapy.

Radiation therapy can take place alone or in combination with other therapies. A combination of radiation therapy with other treatments can improve the likelihood of the treatment being more effective.

A combination of radiation therapy can take place:

  • Before surgery: The combination of radiation therapy with chemotherapy before surgery can shrink large cancers. This, in turn, can help prevent the use of extensive surgeries.
  • After surgery: Combining radiation therapy with chemotherapy after surgery can help kill cancer cells that were too small and remained during surgery. It can also help reduce the risk of the cancer recurring at the same site.
  • With targeted drugs: Radiation therapy can also take place with a targeted drug for large cancers in case chemotherapy is unsuitable.

External-beam radiation therapy (EBRT) is a type of radiation therapy that doctors mostly use to treat oral cancer. EBRT applies radiation from an external source onto the cancer.

The treatment is similar to getting an X-ray but with a stronger dose of radiation and lasts only a few minutes. During the treatment, people must wear a mesh head and neck mask to hold the neck, head, and shoulders in the same position.


There are different types of EBRT. These include:

  • Proton beam radiation therapy: This technique uses protons in place of X-rays. Protons travel specific distances, which helps ensure the tissues behind and in front of the tumor receive minimal radiation exposure.
  • Three-dimensional conformal radiation therapy (3D-CRT): This uses specialized computers to map the exact location of the tumors to prevent damaging healthy cells.
  • Intensity-modulated radiation therapy (IMRT): This is a type of 3D-CRT that uses a computer-driven machine that rotates around the person receiving the radiation. IMRT can adjust the intensity of radiation to prevent damage to nearby healthy tissues.

Brachytherapy, or internal radiation therapy, involves placing radioactive implants in or near the tumor. The implants stay there for 1 to 8 days, during which individuals receive a high radiation dose.

Brachytherapy can also serve as an initial treatment if the cancer recurs.

It is important to regularly follow up with a doctor after radiation therapy. A person should also take care of themselves to help with any side effects that may occur.

These may include:

  • quitting smoking, if applicable
  • getting appropriate nutrition
  • exercising regularly
  • maintaining a moderate weight
  • undergoing dental examinations, blood tests, and imaging tests at regular intervals

The outlook of those with oral cancer depends on the stage of the disease, the area of the mouth it occurs, and the overall health of the person.

People undergoing radiation therapy must also consult a dentist before starting radiation therapy. This is to check if certain teeth issues might increase the risk of infection and if dental treatment is necessary before radiation therapy.

Oral cancer occurs in the oral cavity and oropharynx that can affect talking, chewing, and swallowing. Early detection of this disease can help cure it. Radiation therapy is one of the most common treatment options for oral cancer.

Radiation therapy typically involves two types: EBRT and brachytherapy. Moreover, a combination of radiation therapy can take place with other therapies depending on the stage and severity of the cancer.

However, radiation therapy can cause several side effects. A person should consult their doctor before undergoing radiation therapy to understand the risks and benefits.