How Oral Cancer Is Diagnosed

About 132 people are diagnosed with oral cancer each day in the United States, according to the Oral Cancer Foundation. Perhaps a person undergoes a routine doctor, dental, or self-oral examination that reveals something suspicious, or perhaps it is a symptom, like a non-healing sore or persistent throat pain, that raises concern. Whatever the case, the diagnostic process for oral cancer begins with a visit to an ear-nose-throat (ENT) doctor, which usually involves a head and neck examination, endoscopy, biopsy, and imaging tests to confirm and determine the spread of oral cancer.


While there is no official screening test for oral cancer, many experts and professional groups, like the American Association of Oral and Maxillofacial Surgeons, recommend periodic oral self-exams.

The point of self-exams is to detect oral cancer early before it spreads and becomes more difficult to treat and cure. 

Here are the steps you can take to perform a self-exam. Of course, if you detect anything suspicious, like an abnormal lump or sore that bleeds easily, be sure to call and make a prompt appointment with an ENT doctor. 

  • Step 1: Look into a mirror with a bright light and remove any dentures.
  • Step 2: Examine your face and neck, including below your lower jaw, for any bulges, lumps, growths, sores, or changes in skin color isolated to one side. Using the pads of your fingers, press along the sides and front of your neck, looking for bumps, lymph node swellings, and tenderness.
  • Step 3: Pull your lower lip down and then your upper lip up to examine for sores or color changes on the lips and front of the gums. Using your thumb and forefinger, press gently on your upper and lower lip and gums to check for any lumps or texture changes. 
  • Step 4: Pull each cheek out (so you can see the inside surface) and look for precancerous lesions, which are red patches (called erythroplakia) and white patches (called leukoplakia). Hold each side of your check between your thumb and index finger, and press around for any growths or areas of tenderness.
  • Step 5: Tilt your head back and open your mouth to inspect for and press on any lumps. Take a close look to see if the color is different in an area. 
  • Step 6: Pull out your tongue to inspect all surfaces, looking for lumps or color change. Press on your tongue, including the floor of the mouth underneath it, to feel for any swelling or texture changes. 

Physical Examination

A head and neck examination may be performed by an ENT doctor or by a family doctor or dentist during a routine healthcare visit. During the head and neck exam, your healthcare provider or dentist will look inside your mouth with a light and mouth mirror to best visualize all surfaces. In addition, he will feel around in your mouth (using a gloved finger) for any lumps or areas of swelling or tenderness. The healthcare provider will also press on your neck to see if there are any enlarged lymph nodes, which could be a sign that oral cancer (if present) has begun to spread.


There are two types of procedures that may be used in the process of evaluating a possible case of oral cancer—one, endoscopy, that may only be used in some instances and another, biopsy, that is required for a formal diagnosis.


In addition to a head and neck exam, an ENT doctor may perform an endoscopy to better examine your throat. During an endoscopy, the ENT doctor will place a thin, flexible instrument into your mouth and slide it down your throat. This instrument, called an endoscope, has a camera and light on its tip, so otherwise, hard-to-see areas can be visualized.

Sometimes a more extensive endoscopy procedure called a panendoscopy is required. A panendoscopy entails the use of several types of scopes to visualize all parts of the mouth, throat, voice box, nose, and even the esophagus and/or windpipe. Due to the complexity of this procedure, it's usually performed under general anesthesia in an operating room.


In order to confirm an oral cancer diagnosis, an ENT doctor must take a biopsy (a tissue sample) of the concerning area. The tissue sample is then analyzed under a microscope by a healthcare provider called a pathologist. If a pathologist concludes that cancer cells are present, the biopsy will be tested for the presence of human papillomavirus (HPV).

In addition to HPV testing, which is important for staging the cancer (establishing the extent of the disease) and determining the best course of treatment, a fine needle aspiration (FNA) biopsy of one or more lymph nodes in the neck may be performed.

During an FNA, a healthcare provider inserts a thin needle attached to a clear tube, called a syringe, into a lymph node. He will then suck out, or aspirate, cells from the suspicious area. These cells are then examined closely under a microscope. 


After the diagnosis of oral cancer is made, the stage of the cancer is defined with the help of imaging tests, such as:

  • Computed tomography (CT) scan: Using a rotating machine, a CT scan provides more detailed images of the organs and tissues in your body than a regular X-ray. With a CT scan, your healthcare provider can visualize where in the head and neck area the cancer is located, and whether or not it has grown into nearby tissues, lymph nodes, or distant organs, like the lungs. 
  • Magnetic resonance imaging (MRI): MRI scans use radio waves and a magnetic field (not radiation) to provide detailed images of the body. Compared to a CT scan, an MRI may be more useful for evaluating tongue cancer and superficial tumors of the head and neck.  
  • Positron emission tomography (PET) scan: During a PET scan, a radioactive tracer is attached to sugar and injected into your bloodstream. Then, as you lay still on a PET scanning bed, a special camera takes pictures of your whole body. Since cancer cells metabolize sugar more rapidly than healthy cells, areas of cancer spread will "light up" from the high radioactivity. A PET scan may be combined with a CT scan (called a PET/CT). 


Defining the stage of oral cancer is essential for determining a person's treatment plan and predicting their outcome (called prognosis).

HPV Status

If the cancer is within the oropharynx (the back and middle region of the throat, including the base of the tongue and tonsils), the first step in the staging process is to determine whether the cancer is HPV positive or negative. An HPV positive oropharyngeal cancer means that the tumor makes too many copies (called overexpression) of the protein p16. HPV negative oropharyngeal cancer means that the tumor does not overexpress p16. Overall, HPV positive oropharyngeal cancer has a better prognosis than HPV negative oropharyngeal cancer.

Once the HPV status of a cancer is determined (if its located within the oropharynx), the stage of the cancer is accessed, based on the American Joint Committee on Cancer (AJCC) TNM system.

The AJCC system uses three main parameters:

  • Tumor (T): Describes the size of the cancer and which tissues (if any) it has spread to
  • Lymph nodes (N): Describes whether the cancer has spread to any nearby lymph nodes
  • Metastasis (M): Describes whether the cancer has spread to distant organs in the body, like the lungs

To define the stage of the cancer, numbers are placed after TNM (T 0-4, N 0-3, M 0-1). Higher numbers indicate the cancer is more advanced. For example, the designation, T1, means the cancer size is 2 centimeters or smaller. T2 means the cancer is bigger than 2 centimeters but smaller than 4 centimeters.

The letter/number code is then translated into an overall stage (I, II, III, IV) using a standard chart. For example, a T1N0M0 cancer, which means the cancer is smaller than 2 centimeters and has not spread to lymph nodes or distant organs, is an AJCC stage I cancer.

Infection with certain strains of HPV is an important risk factor for oral cancer.

Pathologic Versus Clinical Stage

It's important to note that the AJCC system uses two staging systems, the pathologic (also called the surgical stage) and the clinical stage.

The pathologic is determined during an operation, as the surgically-removed cancerous tissue is examined. Only patients undergoing surgery (the majority) receive a pathologic stage. All patients undergo a clinical stage, which is based on findings from the physical exam, endoscopy, biopsy, and imaging tests.

While there are separate pathologic and clinical TNM stage grouping systems (the letter/number codes) for HPV positive oropharyngeal tumors, there is no separation of stage groupings for HPV negative oropharyngeal cancer or oral cavity cancer (which includes the lips, cheeks, gums, front two-thirds of the tongue, and the floor and the roof of the mouth).

Summarized below is the pathologic staging for HPV positive oropharyngeal cancer, as well as staging for HPV negative oropharyngeal cancer and oral cavity cancer.

HPV Positive Staging

  • Stage 1: The cancer is 6 centimeters or smaller on the same side as the primary tumor and possibly spread to one or more lymph nodes (but not more than four) 
  • Stage 2: The tumor is either 4 centimeters or smaller but has spread to but has spread to one or more lymph nodes on the opposite side of the neck or both sides. Alternatively, the tumor is larger than 4 centimeters, has extended to the lingual surface of the epiglottis, or has invaded local structures like the larynx (the organ that houses your vocal cords), but has only spread to a maximum of four lymph nodes (if any)
  • Stage 3: The tumor is 4 centimeters or larger, has extended to the lingual surface of the epiglottis, or has invaded local structures like the larynx AND spread to five or more lymph nodes
  • Stage 4: The cancer has spread to distant organs, like the lungs or bones.

HPV Negative Staging

  • Stage 1: The cancer is 2 centimeters or smaller and remains within the mouth or throat; it has not spread to any lymph nodes.
  • Stage 2: The cancer is between 2 and 4 centimeters in size, but has not spread to nearby lymph nodes. 
  • Stage 3: The cancer is either larger than 4 centimeters but not spread to any lymph nodes, or the cancer is of any size but has spread to one lymph node on the same side of the cancer (lymph node is 3 centimeters or less).
  • Stage 4: The tumor is moderately advanced local disease (the cancer has invaded local structures, like the larynx) or very advanced (the cancer has invaded further out structures like the skull base) regardless of whether it has spread to zero, one, or multiple lymph nodes OR the tumor is of any size and has spread to one or more lymph nodes (greater than 3 centimeters); there is no evidence of extranodal extension (ENE), so no deep muscle or skin invasion. The presence of extranodal extension or metastatic cancer, meaning the cancer has spread to distant organs, like the lungs, is also stage IV.

Oral Cavity Cancer

  • Stage 1: The cancer is 2 centimeters or smaller and its depth of invasion is five millimeters or less; it has not spread to any lymph nodes.
  • Stage 2: The cancer is 2 centimeters or smaller and its depth of invasion is between 5 and 10 millimeters and has not spread to any lymph nodes OR the cancer is between 2 and 4 centimeters in size with a depth of invasion of 10 or less millimeters; it has not spread to nearby lymph nodes. 
  • Stage 3: The cancer is either larger than 4 centimeters or has a depth of invasion greater than 10 millimeters AND has spread to no lymph nodes or one lymph node on the same side of the cancer. Alternatively, the cancer is less than 4 centimeters with a depth of invasion less than 10 millimeters and has spread to a 3 centimeter or less lymph node on the same side of the cancer with no extranodal cancer extension.
  • Stage 4: The tumor is considered moderately or very advanced (the cancer has invaded local structures), regardless of whether it has spread to zero, one, or multiple lymph nodes. Alternatively, the tumor may be of any size and the cancer has spread to at least one lymph node 6 centimeters or smaller with extranodal cancer extension or larger than 3 centimeters with no extranodal cancer extension. The presence of a larger than 6 cm lymph node, extranodal cancer extension in a lymph node larger than 3 centimeters, or distant metastatic cancer (spread of cancer to distant organs, like lung for example) is also stage 4.
head and neck cancer: stage at diagnosis
Illustration by Verywell

Differential Diagnoses

There are many possible diagnoses when it comes to abnormal-appearing spots, sores, or lesions within the inner lining of the mouth. These diagnoses range from the common canker sore (called an aphthous ulcer) to infections with coxsackie or herpes simplex viruses, as well as autoimmune concerns (for example, Behcet's disease or lupus erythematosus).

In some cases, a healthcare provider can make a diagnosis based on a medical history and physical examination alone.

For example, a person with no risk factors for oral cancer and a classic-appearing canker sore will likely be advised by a practitioner to attempt supportive care, like applying Orabase (benzocaine) over the canker sore for pain relief, and to return to the clinic if the sore does not heal within a week or two. 

If a healthcare provider cannot determine the diagnosis from a medical history and physical examination, or if there is any suspicion for cancer (like bleeding from the mouth or a persistent sore), a tissue sample is critical to ensure an accurate diagnosis. Benign lesions that closely resemble that of oral cancer or pre-cancer may also need to be biopsied for confirmation. Some of these lesions include:

  • Amalgam tattoo
  • Fordyce spots
  • Mucocele

Like mouth lesions, some tongue abnormalities can be diagnosed based on history and appearance alone.

Other tongue conditions may require more testing, like blood tests or a biopsy, to confirm the diagnosis. For example, atrophic glossitis, in which the tongue is tender and appears smooth and glossy on a red or pink background, is associated with vitamin B12 deficiency, which can be diagnosed with a single blood test. 

Frequently Asked Questions

  • Where in the mouth does oral cancer start?

    It varies, but often, signs are first noticed on the floor of the mouth, the area under the tongue. The front part of the tongue and lower gums are also fairly common sites where oral cancer develops. These cancerous growths begin as white patches, red patches, or irritated sores.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Warning Signs of Oral Cancer. American Association of Oral and Maxillofacial Surgeons.

  3. Tests for Oral Cavity and Oropharyngeal Cancers. American Cancer Society. Mar 9, 2018.

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  5. Elrefaey S, Massaro MA, Chiocca S, Chiesa F, Ansarin M. HPV in oropharyngeal cancer: the basics to know in clinical practice. Acta Otorhinolaryngol Ital. 2014;34(5):299-309.

  6. Kansky AA, Didanovic V, Dovsak T, Brzak BL, Pelivan I, Terlevic D. Epidemiology of oral mucosal lesions in Slovenia. Radiol Oncol. 2018;52(3):263-266. doi:10.2478/raon-2018-0031

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Additional Reading

By Tammy Davenport
Tammy Davenport is a dental assistant with experience on the clinical and administrative side.