Causes and Risk Factors of Oral Cancer

According to the American Cancer Society, around 50,000 people will develop cancer of the mouth or throat this year. These cancers develop when abnormal cells that line the inside of the mouth or throat begin to grow out of control. The "why" behind this rapid and aberrant growth is linked to risk factors, like tobacco and alcohol use, which introduce carcinogens (cancer-causing chemicals) into the cells.

But despite myths, they are not the only culprits. Infection with the human papilloma (HPV) virus is another risk factor, mostly for developing cancer of the tongue and tonsils. Other risk factors include non-modifiable ones (for example, having a rare genetic syndrome) and modifiable ones like a diet deficient in fruits and vegetables, excess sun exposure, and poor oral hygiene. 

Common Causes

Oral cancer stems from a change in the DNA of cells that line the mouth or throat. These DNA changes may promote cancer by either creating genes that start cancer cell growth (called oncogenes) or turning off genes that normally stop cancer cell growth (called tumor suppressor genes).

Once abnormal cells that line the mouth or throat begin to grow uncontrollably, a tumor eventually forms and symptoms may begin to manifest.

Here are the risk factors linked to the development of oral cancer.

Tobacco

A risk factor for developing oral cancer is the use of smoking tobacco products, including cigarettes, cigars, and/or pipes.

Nonsmoking tobacco products (for example, snuff, dip, spit, chew, or dissolvable tobacco) are also associated with an increased risk of oral cancer. Research further suggests that secondhand smoke exposure as a child increases the risk of oral cancer as an adult.

Alcohol

Alcohol consumption is linked to the development of oral cancer, and this link is dose-dependent, meaning the more alcohol a person drinks, the higher their risk.

Human Papilloma Virus (HPV)

Human papillomavirus (HPV virus) is the most commonly diagnosed sexually transmitted disease in the United States and is linked to the development of genital warts and various cancers, including cervical, vaginal, penile, and anal cancer. The HPV virus, especially type HPV-16, may also cause oral cancer, most commonly at the base of the tongue and in the tonsils.

The good news is that there is an HPV vaccine. While the vaccine was developed to lower the risk of cervical cancer, research suggests it has decreased the prevalence of oral HPV infection among the vaccinated. This means that there potentially is a decreased risk of oral cancer if a person receives the vaccine, although there is no scientific evidence proving this as of yet. 

Weakened Immune System

People who have a weakened immune system, especially those with HIV or those who have undergone an organ transplant, are at an increased risk for developing oral cancer.

Sun Exposure

Prolonged exposure to the sun's damaging UV rays without a sun protection factor (SPF) lotion applied to any part of your body increases the risk of oral cancer, especially to the lips. 

Personal History 

Having a history of one oral cancer increases the chance of developing a second oral cancer. This is why it's important to get regular check-ups with your ENT doctor, even if your first oral cancer is cured. 

Betel Quid Use

Betel quid chewing is a popular practice in certain parts of Asia and has been associated with the development of oral cancer. Betel quid consists of betel nut, spices, and lime, among other ingredients. Research shows that the risk of developing oral cancer is increased the longer a person uses betel quid and the more they chew per day.

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Genetics

Having a family history of oral cancer is a risk factor, as some gene mutations (linked to cancers of the mouth and throat) can be passed down from parent to child; that said, most cases of oral cancer are not inherited. 

Besides having a family history of oral cancer, there are specific genetic syndromes that increase the risk of developing oral cancer. 

Fanconi Anemia

Fanconi anemia is a rare inherited syndrome that is associated with bone marrow failure, as well as a vulnerability for developing various cancers, including head and neck cancers, and cancer of the esophagus, anus, and urogenital region (for example, bladder and kidney).

Dyskeratosis Congenita

Dyskeratosis congenita is a rare inherited syndrome characterized by abnormal nails, skin color changes on the neck and chest, and white patches in the mouth (called leukoplakia); these white patches predispose individuals to cancer of the mouth and throat.

Lifestyle Risk Factors

Besides tobacco and alcohol use, several other lifestyle-related risk factors are linked to oral cancer.

Diet Deficient in Fruits and Vegetables

A diet low in vegetables can increase the risk of oral cancer. By increasing your fruit and vegetable intake, especially from the following groups, you can decrease your risk of oral cancer.

Mouthwash Use

Although still an emerging risk factor, research suggests that long-term, frequent use of mouthwash (over 35 years, more than once per day) is linked to the development of oral cancer. This is because most mouthwash products contain alcohol. 

Poor Oral Hygiene

Poor oral hygiene may increase the risk for oral cancer. Regular dental care, brushing, and flossing may lessen this risk.