How Can You Tell If a Mouth Sore Is Cancerous?

Medically Reviewed on 6/21/2022
How Can You Tell if a Mouth Sore Is Cancerous?
Oropharyngeal or oral cancer is the most common form of head and neck cancer.

Oral cancer can be detected early by:

  • A monthly self-examination
  • Use a bright light and a mirror to look at the lips and front of the gums
  • Tilt your head back and look at the roof of the mouth
  • Pull your cheeks out to view the inside of the mouth, the lining of the cheeks, and the backside of the gums
  • Pull out your tongue and look at all surfaces, including the floor of the mouth
  • Feel for lumps or enlarged lymph nodes on both sides of the neck and under the lower jaw
  • If you notice changes or something unusual, contact your dentist immediately

The American Cancer Society recommends oral cancer screening examinations every three years for people older than 20 years and annually for those older than 40 years.

It is common to get confused between two different types of oral issues: mouth or canker sores and mouth or oral cancer.

The table shows differentiating points that could help distinguish between the two. These are not definitive signs, and only a biopsy can tell for sure if the sore is cancerous.

Mouth sore vs. oral cancer chart

Table. Difference between mouth sores and oral cancer
Differentiating points Mouth sore Oral cancer
Shape Tiny, round-shaped Flat, red, white, or brown patches
Location On the cheeks, lips, tongue, back of the throat, or base of the gums Can grow anywhere in the mouth but typically affects the tongue, lips, throat, or cheeks
Causes Hormonal shifts, stress, toothpaste, and food sensitivities
  • Age older than 50 years
  • People who consume tobacco or alcohol are more vulnerable to developing mouth cancer
Major or minor issues Harmless Harmful
Pain tendency Temporary pain with just a little discomfort Painless
Resolution Often go away on their own within 7 to 14 days and, in rare cases, a larger sore may need a couple of months to heal Oral cancer patches do not heal within this timeframe
Treatment Rarely needed Always needed
Look Always flat, have a yellow or white center and turns gray as they start to heal Can be raised or flat and are often white, red, or brown
Spread Usually does not spread to other areas of the mouth If left untreated, oral cancer can spread throughout the mouth, throat, and other areas of the head and neck
Other difficulties Does not lead to problems with speaking, chewing, or swallowing Causes problems with speaking, chewing, or swallowing


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What is oral cancer?

Oropharyngeal or oral cancer is the most common form of head and neck cancer that typically affects the:

  • Lips
  • The first part of the tongue
  • Oropharynx (includes the last part of the tongue, roof of the mouth, tonsils, sides, and back of the throat)

It can cause white patches or sores that bleed. Approximately 63 percent of people can live for five years after diagnosis.

Oral cancer starts in the squamous cells of the oral cavity when their DNA changes and cells begin to grow and multiply uncontrollably. Over time, these cancerous cells can spread to other areas inside the mouth, head, and neck.

8 risk factors for developing oral cancer

  1. According to the American Cancer Society, men have two times more risk of developing oral cancer than women
  2. Age older than 50 years
  3. A family history of oral cancer
  4. Smoking cigarettes, cigars, or pipes
  5. Use of smokeless tobacco products, such as chewing tobacco, dip, snuff, or water pipes (hookah or shush)
  6. Regular and excessive amounts of alcohol consumption
  7. Excessive sun exposure, especially at a young age without lip protection with sunblock
  8. Human papillomavirus infection

How to determine if a mouth sore is cancerous

The doctor (a dentist or an ear, nose, and throat specialist) may spot potential oral cancer during regular checkups.

They may follow up with preliminary tests, medical, or family history, and current symptoms to rule out oral cancer.

To confirm a diagnosis of oral cancer, the following tests are recommended:

  • Physical examination: The healthcare provider will see the inside of the mouth along with the examination of the head, face, and neck for potential signs of precancer or cancer.
  • Brush biopsy, scrape biopsy, or exfoliative cytology: A small brush or spatula is used to gently scrape the area in question to obtain cells examined for cancer.
  • Incisional biopsy: Small pieces of tissue are removed to be examined under the microscope for cancerous changes.
  • Indirect laryngoscopy and pharyngoscopy: A small mirror on a long thin handle is used to look at the throat, the base of the tongue, and part of the larynx.
  • Direct or flexible pharyngoscopy and laryngoscopy: An endoscope (a thin, flexible tube with an attached light and viewing lens) is used to look at the areas of the throat and mouth that cannot be seen using mirrors.

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Medically Reviewed on 6/21/2022
Image Source: iStock image

Cleveland Clinic. Oral Cancer.

WebMD. Oral Cancer: Risks, Symptoms, and Prevention.