Squamous Cell Carcinoma of the Oral Cavity

Squamous cell carcinoma of the oral cavity is a serious cancer affecting the mouth, accounting for more than 90% of all oral malignancies. Early detection is crucial, as this disease often shows no symptoms in its early stages when it is most treatable.

Table of contents

• What is Squamous Cell Carcinoma of the Oral Cavity?
• Affected Areas of the Mouth
• How Common is This Cancer?
• Risk Factors
• Symptoms and Warning Signs
• How Doctors Diagnose This Cancer
• Treatment Options
• Outlook and Survival
• Prevention

What is Squamous Cell Carcinoma of the Oral Cavity?

Squamous cell carcinoma of the oral cavity is a type of cancer that develops in the mouth. It starts in the squamous cells, which are flat, thin cells that line the lips and the inside of the mouth^[1]. When viewed under a microscope, these cells look like fish scales^[3].

The cancer begins when the DNA of these cells changes, causing them to grow and multiply abnormally. Over time, these cancerous cells can spread to other areas inside the mouth, and then to other parts of the head and neck or other areas of the body^[3].

Oral cancer refers to cancer occurring between the border of the lips and the junction where the hard and soft parts of the roof of the mouth meet, or the back third of the tongue^[1]. As with most head and neck cancers, squamous cell carcinoma is the most common type found in the oral cavity^[1].

Affected Areas of the Mouth

• Lips
• Gums
• Tongue (front two-thirds)
• Floor of the mouth (under the tongue)
• Hard palate (roof of the mouth)
• Buccal mucosa (lining of the inside of the cheeks)
• Retromolar trigone (the small area behind the wisdom teeth)

The cancer can develop in any of these areas. The tongue and floor of the mouth are the most common sites for this type of cancer^[2]. Specifically, the back and side surfaces of the tongue and the floor of the mouth are frequent starting points for these cancers^[1].

How Common is This Cancer?

Oral squamous cell carcinoma affects about 35,000 people in the United States each year^[1]. In the United States, 3% of cancers in males and 2% in females are oral squamous cell carcinomas, and most occur after age 50^[1].

According to data collected worldwide, there were 377,713 cases of this cancer in 2020, with the majority occurring in Asia^[7]. The disease affects more males than females, with middle-aged to elderly men being the most susceptible^[7].

Between 6,000 and 7,000 deaths per year occur because of oral cavity cancer^[5]. The Global Cancer Observatory predicts that the number of cases will rise by approximately 40% by 2040, accompanied by a growth in mortality^[7].

Risk Factors

Over 95% of people with oral squamous cell carcinoma smoke tobacco, drink alcohol, or both^[1]. Understanding these risk factors is important for prevention.

Major Risk Factors

Tobacco use is the most significant risk factor for oral cavity cancer. Smoking cigarettes, especially more than two packs per day, dramatically increases risk^[1]. The risk of developing oral cancer is three times higher in people who smoke compared to people who do not smoke^[8]. Chewing tobacco or betel quid can also increase a person’s risk^[8].

Alcohol consumption also increases risk. The risk increases dramatically when alcohol use exceeds 177 mL (6 oz) of distilled liquor, 148 mL (5 oz) of wine, or 1065 mL (36 oz) of beer per day^[1]. A person who combines smoking and drinking alcohol is around 30 times more likely to develop oral cancer than people who do not smoke or drink^[8]. The combination of heavy smoking and heavy alcohol consumption is estimated to raise the risk 100-fold in females and 38-fold in males^[1].

Other Risk Factors

Additional factors that can increase risk include:

• Human papillomavirus (HPV) infection, typically acquired through oral-genital contact, may play a role in some oral cancers, though it is identified in oral cancer much less often than in throat cancer^[1]
• Chronic irritation from dental cavities, overuse of mouthwash, or chronic dental trauma^[1][2]
• Prolonged sun exposure, especially to the lips^[8]
• Excess body weight^[8]
• Consuming a diet low in fruits and vegetables^[8]
• Being male^[8]
• Age over 55 years^[8]
• Certain genetic syndromes, such as Fanconi anemia and dyskeratosis congenita^[8]

It’s important to note that 25% of people who develop oral cancer don’t smoke or have other known risk factors^[3]. Oral squamous cell carcinoma appears distinct in non-smoking and non-drinking individuals and in younger ages^[2].

Symptoms and Warning Signs

Early, curable lesions are rarely symptomatic, highlighting the need for oral screening^[1]. Oral lesions are usually painless at first^[1]. This is why catching the disease early through regular dental checkups is so important.

Early Warning Signs

The lesions may appear as areas of erythroplakia (red patches) or leukoplakia (white patches) and may be raised or ulcerated^[1]. Early-stage lesions can appear as flat, discolored areas^[2].

Visible signs may include:

• A sore on the lip or inside the mouth that does not heal within two weeks^[3]
• White or red patches in the mouth that cannot be scraped away^[3]
• A lump or thickening in the lips, mouth, or cheek^[3]
• Rough spots or crusty areas on the lips, gums, or inside of the mouth^[3]
• Areas in the mouth that bleed for no obvious reason^[3]

Progressive Symptoms

Cancers are often firm and hard to the touch with a rolled border^[1]. As the lesions increase in size and the disease progresses, additional symptoms may develop:

• Pain that does not go away^[1]
• Difficulty speaking (dysarthria)^[1]
• Difficulty swallowing (dysphagia)^[1]
• A sore throat that does not go away^[3]
• A feeling that something is caught in the throat^[3]
• Numbness in the tongue, lip, or other area of the mouth^[3]
• Loosening of the teeth or tooth mobility^[2]
• Jaw pain or swelling, or difficulty moving the jaw (trismus)^[2][3]
• Changes in the voice or persistent hoarseness^[2]
• Ear pain^[3]
• A mass or lump in the neck^[2][3]
• Unexplained weight loss^[3]

How Doctors Diagnose This Cancer

Tests that examine the mouth and throat are used to diagnose and stage lip and oral cavity cancer^[3]. Dentists and oral specialists play an essential role in the early detection and diagnosis of oral squamous cell carcinoma^[2].

Physical Examination

A doctor will begin by asking about symptoms and possible risk factors. During a physical examination, the doctor will carefully inspect the mouth, throat, and neck, looking for abnormalities^[8]. Dentists often are the first to detect oral lesions during routine physical examination of the oral cavity^[2].

Biopsy

If suspicious areas are found, a biopsy is necessary to confirm the diagnosis. During a biopsy, a small sample of tissue is removed and examined under a microscope by an oral pathologist to look for cancer cells and histopathological features of malignancy^[2].

Additional Tests

Advanced diagnostic techniques may also be used, such as molecular biology and cytology, to identify malignant or pre-malignant oral lesions^[2]. The clinical appearance of oral squamous cell carcinoma can resemble other common oral lesions, emphasizing the need for careful examination^[2].

Treatment Options

Treatment is with surgery, radiation, or both, although surgery plays a larger role in the treatment of most oral cavity cancer^[1]. Treatment for oral squamous cell carcinoma is multidisciplinary and depends on the location, the stage of the disease, and the patient’s overall health status^[2].

Surgery

For early-stage cancer, surgery is often the first-line treatment^[2]. The goal is to remove the cancer completely. Early stage lesions (smaller than 4 cm and less than 1 cm in depth) should be removed with margins of 1.0 to 1.5 cm around the tumor^[5].

For advanced-stage cancers (larger than 4 cm and invasive beyond 1 cm), more extensive surgery may be needed. The most important aspect is determining whether the cancer can be removed. Lesions that involve the skull base or major blood vessels may not be removable^[14].

Radiation Therapy

Radiation therapy uses high-energy beams to kill cancer cells. It can be used alone or combined with other treatments^[2]. Radiation therapy has been described as a primary treatment for selected lesions^[14].

Systemic Therapy

Systemic therapies, including chemotherapy (drugs that kill cancer cells) and targeted therapy (drugs that target specific features of cancer cells), are typically the choice for advanced or metastatic disease^[2]. In some cases, chemotherapy may be given before surgery (neoadjuvant chemotherapy) to shrink the tumor^[14].

Combined Approaches

Surgical therapy followed by additional treatment is the preferred management approach for all removable cancers^[14]. Many patients receive a combination of treatments to achieve the best outcome.

Outlook and Survival

The outlook for oral squamous cell carcinoma depends largely on the stage at which it is diagnosed. Approximately 63% of people with oral cavity cancer are alive five years after diagnosis^[3].

Early-stage cancers have a better prognosis than advanced-stage cancers^[2]. The disease is characterized by a high rate of mortality and recurrence^[4]. Most cancers that return do so within the first two years after treatment^[3].

Factors Affecting Prognosis

Several factors influence survival and recovery:

• The stage of the disease at diagnosis
• The patient’s age (young adults 40 years and under may have a poorer prognosis)^[2]
• Tobacco and alcohol use history, which can complicate overall health and contribute to other diseases^[2]
• Whether the cancer has spread to lymph nodes or distant organs

The cancer’s progression, local invasion of nearby organs, and distant spread (especially to vital organs like the lungs) are the primary causes of death^[2]. The aggressive growth of lesions can rapidly invade and damage surrounding structures, such as the airway, leading to blockage, bleeding, and severe infections^[2].

Prevention

Prevention strategies are crucial for reducing the incidence of oral squamous cell carcinoma and improving outcomes^[24]. Since early, curable lesions are rarely symptomatic, preventing disease requires early detection by screening^[1].

Lifestyle Changes

The most important preventive steps include:

• Avoid all tobacco products: Do not smoke cigarettes, cigars, or pipes, and avoid smokeless tobacco products such as chewing tobacco or betel quid^[1][24]
• Limit alcohol consumption: Drink in moderation or abstain from alcohol altogether^[3][24]
• Eat a healthy diet: Consume a diet rich in fruits and vegetables^[3][24]
• Protect your lips from the sun: Use sunblock or lip balm with sun protection when outdoors for long periods^[3][24]
• Maintain good oral hygiene: Brush and floss regularly, and address dental problems promptly

Regular Screening

Regular dental checkups are essential for early detection. Dentists can perform oral cancer screenings during routine visits^[2]. Promoting regular dental checkups and early detection through screening programs can significantly reduce the risk of advanced disease^[24].

HPV Vaccination

HPV vaccination programs may help prevent some cases of oral cancer linked to this virus^[24].

Public health policies focusing on reducing tobacco and alcohol use further support efforts to prevent oral cancer^[24]. If you have risk factors or notice any unusual changes in your mouth that last more than two weeks, see a dentist or doctor promptly.