What is Cancer of the Oral Mucosa?
Oral mucosal cancer is a type of cancer that develops in the lining of various parts of the mouth, such as the lips, cheeks, around teeth and gums, front two-thirds of the tongue, bottom of the mouth, roof of the mouth, and at the back near the wisdom teeth. The mouth area is situated very close to the oropharynx, which includes parts like the lower part of the soft palate, division between front and back parts of the tongue, and in front of the tonsils. This close location helps in differentiating the structures of the mouth particularly the soft palate, from the structures of the oropharynx like the faucial and lingual tonsils located at the base of the tongue. Clear differentiation is crucial for accurate diagnosis and treatment planning.
Smoking and alcohol consumption are significant risk factors for oral mucosal cancer, and the risk increases considerably when these habits are combined. Other risks may come from human papillomavirus (HPV) infection and stem cell transplants. The main method of treating oral mucosal cancer is surgery, and in advanced cases, it often includes the use of radiotherapy, which is a treatment method using high-energy radiation to kill cancer cells.
What Causes Cancer of the Oral Mucosa?
Understanding the various causes of mouth cancer is crucial for effective prevention and early detection. Various factors, such as using tobacco and alcohol, HPV infections, and stem cell transplants, play a role in the development of mouth cancers.
Tobacco use, particularly smoking, is the most significant risk factor for developing oral cancer because it introduces cancer-causing chemicals into the body, such as nitrosamines, benzopyrenes, and aromatic amines. Smokers are three times more likely to get mouth cancer than non-smokers. Individuals can also be at risk from passive smoking, particularly with consistent exposure to second-hand smoke. Alcohol use alongside smoking can significantly increase the risk of cancer.
In some parts of the world, people use tobacco by chewing it or holding it in their mouths instead of smoking. This form of tobacco use has also been linked to oral cancers due to the tobacco’s direct contact with the mouth’s tissues. Chewing a mixture of betel leaf, areca nut, slaked lime, and tobacco, a practice common in South Asia and some parts of Micronesia, has been associated with a higher risk of cancer compared to smoking tobacco alone because the cancer-causing substances are in the mouth for a longer period. People in Scandinavia and North America often use a moist form of smokeless tobacco, known as snuff or snus, placing it under the upper lip for extended periods.
Drinking alcohol, especially alongside smoking, can increase the risk of mouth cancer. While alcohol itself does not cause cancer, it does make the lining of the mouth more prone to damage from other cancer-causing substances.
Human Papillomavirus (HPV), particularly types 16 and 18, can increase the chances of developing certain types of cancer, including cervical and oropharyngeal (cancer in the part of the throat located at the back of the mouth). While the link between HPV and mouth cancers is not as well-established, evidence does suggest such a connection. HPV infection happens more often in individuals with squamous cell carcinomas (a type of skin cancer) than in those with healthy mouth lining. The primary way HPV spreads is through oral sexual contact.
Finally, individuals who have had stem cell transplants are much more likely to develop oral cancer than the general population, 4 to 7 times more. A condition often seen in the mouth as a consequence of a stem cell transplant, called graft-versus-host disease, is often followed by the onset of cancer. The most common symptoms of this condition include painful inflammation and sores in the mouth, dry mouth, and mouth lesions that resemble lichen planus. Oral cancers most often develop in the tongue and salivary glands around 5 to 9 years after a transplant. Organ transplant recipients, due to the necessary immunosuppression, also exhibit higher susceptibility to oral cancers.
Risk Factors and Frequency for Cancer of the Oral Mucosa
Telling the difference between the number of new cases and the total number of cases of oral cavity cancers can be tricky because of different categorization methods. Even though they are two separate diseases, a lot of old national databases still lump their information together. The 4th edition of the American Cancer Society’s Global Cancer Facts and Figures report in 2018 stated that these types of cancer make up about 2% of all cancers worldwide. For males living in countries with a medium Human Development Index, lip and oral cavity cancer, along with lung cancer, are among the most often diagnosed.
While the number of oropharyngeal cancers, especially those caused by HPV, is increasing, the number of oral cavity cancers is going down. Countries in South Asia, such as India and Sri Lanka, as well as the Pacific Islands, see the most instances of oral cavity and lip cancers in the world. The rate is around twice as high in males as it is in females. This could be because males more often engage in behaviors that cause cancer, like smoking and drinking alcohol.
- The difference between new and total oral cavity cancer cases can be hard to identify.
- Many databases still combine data on lip and oral cavity cancer.
- These cancers account for about 2% of all cancers worldwide.
- Lip and oral cavity cancers are often diagnosed in males in medium Human Development Index countries.
- The rate of oropharyngeal cancers is increasing, while the rate of oral cavity cancers is decreasing.
- South Asian countries and the Pacific Islands see the most cases.
- The rate is about twice as high in males, possibly due to behaviors like smoking and drinking.
Signs and Symptoms of Cancer of the Oral Mucosa
Oral mucosal cancer, or cancer that occurs in the mouth, appears in a variety of ways depending on the specific area affected. Early stages can present as irregular white, red or mixed patches on the inside of the mouth. As the cancer worsens, hardened raised lumps with an ulcerated surface often emerge. If the cancer reaches the tongue, it can lead to slurred speech or difficulty sticking out the tongue fully due to pain or the tongue being tethered. Cancer located in the alveolar ridge, or the bony part of the mouth where teeth are anchored, can result in loose teeth nearby. When the cancer expands locally or throughout the body, patients may have difficulty swallowing, painful swallowing, a raspy voice, ear pain, weight loss, and swollen glands in the neck.
A detailed examination of the oral cavity is crucial in spotting potential tumors, uncovering multiple tumors, or catching the spread of cancer. This check includes using two tongue depressors and a good light source, in addition to a neck examination for swollen glands. Swollen glands in the neck are recorded based on their anatomical level, ranging from I to VI. It’s also recommended to use a flexible endoscope passed through the nose to check for simultaneous tumors in the throat or voice box.
- Irregular white, red or mixed patches inside the mouth
- Hardened raised lumps with an ulcerated surface
- Slurred speech or trouble sticking out the tongue fully
- Loose teeth
- Difficulty swallowing or painful swallowing
- Hoarse voice
- Ear pain
- Weight loss
- Swollen glands in the neck
Testing for Cancer of the Oral Mucosa
To correctly identify and determine the severity of oral mucosal cancer, a thorough check-up process is employed. This involves physical examinations, tissue sample tests (biopsies), specialized viewing of the oral cavity (endoscopic procedures), and body imaging scans.
Biopsy
A biopsy is an important first step in exploring oral cancer signs. If the patient can comfortably handle it and the area can be easily reached, many oral tests can be carried out in a regular doctor’s office. For enlarged lymph nodes, a fine needle may be inserted at the spot and guided by ultrasound to draw a tissue sample. For lesion locations that are harder to reach such as the base of the tongue or areas further back, the patient might have to be put under general anesthesia (induced sleep) so that a safe sample collection can be performed.
Endoscopy
Endoscopy, a process that uses a thin tube with a light and a camera to view inside your body, can provide useful insights. A complete endoscopy done under general anesthesia is necessary for a full examination of accompanying tumors in the throat and voice box (pharynx and larynx), as it facilitates a more detailed evaluation. This method can check the tumor’s mobility, identify its depth, and spot any attachment to nearby structures.
Imaging
Computed tomography (CT) scans with an injected contrast solution are critical for a detailed assessment. These scans can measure the local spread of the tumor, involvement with bones or nearby structures, lymph nodes, and the chest. If a patient cannot tolerate the contrast solution typically used, magnetic resonance imaging (MRI) can be a substitute. Also, positron emission tomography (PET) scans can help evaluate unclear cases or late-stage diseases by detecting distant cancer spreads (metastases).
Treatment Options for Cancer of the Oral Mucosa
Early-stage cancers (known as stage I or II) often receive single treatment types, such as surgery (removal of the main cancerous growth along with the tissue surrounding it) or radiation therapy (a process that targets the main cancer site and surrounding neck areas potentially at risk). Specifically for mouth cancer, surgery has been found to provide better control of the disease and fewer side effects compared to non-surgical treatments, but this result is not commonly seen in other kinds of head and neck cancers.
Late-stage cancers (known as stage III or IV), however, usually need several types of treatment. After surgery, patients might receive radiation therapy (even coupled with chemotherapy or immunotherapy), or a combination of chemotherapy and immunotherapy, along with radiation therapy.
The extent of the surgery depends on factors like the size, location, and stage of the tumor. If the cancer has spread to the tongue, a partial or total removal of the tongue (known as a glossectomy) may be performed. If the cancer is in the cheek lining or the soft part of the roof of the mouth, it can be removed through a process called wide local excision. For cancer on the hard part of the roof of the mouth, a procedure known as maxillectomy is used. Depending on whether the tumor is superficial or deep, a marginal or segmental mandibulectomy is performed for tumors on the lower jaw. Lip tumors are managed with wide local excision or wedge excision.
If there is evidence that the cancer has spread locally or to the lymph node, neck dissection may be recommended. In cases where there is a high risk of spread but no clinical evidence, a sentinel lymph node biopsy (a procedure that finds the first few lymph nodes into which a tumor drains) may be considered. It is important to examine the removed tumor under a microscope to ensure that the whole tumor, including its boundaries, has been removed.
Radiation therapy is often used alongside surgery and either chemotherapy or immunotherapy to target the tumor and areas at risk of spreading. However, radiation to the head and neck region often causes significant inflammation of the mouth lining, which can lead to painful swallowing and nutritional challenges. As a result, patients may require alternative feeding methods for some time. Long-term effects of radiation may include changes in taste, dry mouth, and changes in the esophagus, some of which can be permanent.
The treatment for head and neck cancer generally includes platinum-based chemotherapy, such as cisplatin or carboplatin, but this is not used as a standalone cure; instead it’s typically used alongside radiation therapy. Chemotherapy is also often used in palliative care treatments, which aim to relieve symptoms rather than cure the disease.
Immunotherapy, such as cetuximab or pembrolizumab, can also be used. These treatments aim to stimulate the body’s natural defenses to fight the cancer. They are often applied to locally advanced, recurrent, or metastatic diseases and are typically combined with other palliative care interventions.
When aggressive or advanced tumors or significant other illnesses prevent curative treatment, palliative care, which aims to relieve symptoms and improve quality of life, becomes the most suitable option for patients. This often includes palliative radiotherapy along with medications aimed at symptom management and improving end-of-life care.
What else can Cancer of the Oral Mucosa be?
When trying to diagnose oral mucosal lesions, doctors consider several possibilities. These conditions can include:
- Pre-cancerous lesions, such as Erythroplakia and leukoplakia
- Benign oral mucosal lesions, including Geographic tongue, median rhomboid glossitis, necrotizing sialometaplasia, hairy tongue, oral hairy leukoplakia, oral candidiasis, herpetic gingivostomatitis, aphthous ulcers, traumatic ulcers, and herpes labialis.
- Benign tumors like Papilloma, lipoma, lingual thyroid, mucocele, ranula, neurofibroma, haemangioma, and oral keratoacanthoma
- Odontogenic tumors (tumors related to tooth development)
It’s important for the medical professional to consider all these conditions and carry out suitable tests to make a correct diagnosis.
What to expect with Cancer of the Oral Mucosa
The outlook and survival rates in cancer strongly depend on how progressed the disease is at the time of diagnosis, how quickly and adequately it’s treated, and the capabilities of local health providers. Survival rates over five years can drop considerably when cancer spreads in the local area and drop even further if the cancer spreads to distant parts of the body. These trends underline the importance of catching and diagnosing cancer early to improve chances of surviving the disease.
According to the American Cancer Society, survival rates for cancers of the mouth and throat vary in different situations. If the cancer is only found in the area it started, the 5-year survival rate is about 84%. However, this rate decreases to 66% for those with cancer spread locally and 39% when the cancer has spread to far regions of the body. It’s worth noting that individuals with HPV-positive cancers generally have better survival rates.
Because survival rate data often lump mouth and throat cancers together, especially considering the higher occurrence of HPV-positive cancers in the throat, it’s difficult to provide an exact survival rate for mouth cancer on its own. However, we do know that cancer often comes back in mouth squamous cell carcinoma, the most common type of mouth cancer. This can happen at the original site, in the lymph nodes, or in distant organs like the lungs, liver, or bone. When cancer comes back, it is often associated with considerably high death rates, and early return of the cancer usually suggests a worse outlook.
Possible Complications When Diagnosed with Cancer of the Oral Mucosa
Complications in oral mouth cancer can occur if the disease is not treated or if there are side effects from the treatments. Surgery has risks. For example, the surgeries to remove the tumor or reconstruct the mouth might not work, the surgical wound might split open, local movement and feeling nerves might be damaged, vocal cords may become paralyzed, and patients might have difficulty opening their mouth, speaking clearly, and might need to rely on breathing or feeding tubes for a long time. These complications may require some patients to stay longer in intensive care.
The treatments of chemotherapy or radiotherapy can cause a variety of chronic and debilitating symptoms. For example, in oral mouth cancer, patients often experience inflamed mucous membrane in their mouth, pain, bleeding, difficulty in opening mouth, and dry mouth. These symptoms, combined with difficulty swallowing, can lead to not eating enough and malnutrition. It’s also common for patients to have difficulty speaking and need help from speech and language therapists. Also, the system-wide effects of the treatments can lead to low neutrophil blood cell count which can increase the risk of infections due to lowered immunity.
The emotional toll of being diagnosed with cancer, coupled with these complications and side effects from treatment, can have a severe and long-lasting effect on a person’s mental health and overall quality of life. Studies show that about 50% of patients with head and neck cancer experience depression, which emphasizes the significant mental health issues that these individuals face.
Common Complications:
- Surgical risks like failure of reconstruction, wound opening, nerve damage and vocal cord paralysis
- Problems like difficulty in opening mouth, clear speech, and possible dependency on breathing or feeding tubes
- Long stay in intensive care
- Side effects of treatment like inflamed mucous membrane, pain, bleeding, dry mouth
- Dietary issues leading to malnutrition due to swallowing difficulties
- Needs for speech and language therapy
- Lowered immunity leading to increased infection risk
- Depression and lowered overall quality of life
Preventing Cancer of the Oral Mucosa
The main way to prevent oral cancer is by making changes to your lifestyle to lessen its major risk factors. This includes getting advice on how to quit smoking, learning about safe levels of drinking alcohol, and advocating for a nutritious diet. These key practices are not only important messages for the public to stop the occurrence of oral cancer, but they also play a significant part in helping people who have been diagnosed with the disease to keep it from coming back.
