Keratinising Squamous Cell Carcinoma of Nasopharynx

Keratinising squamous cell carcinoma of the nasopharynx is a distinct type of throat cancer that forms in the upper part of the throat behind the nose, where cancer cells are covered with a protein called keratin.

Table of contents

• What Is This Type of Cancer
• Where It Develops
• How It Differs From Other Types
• How Common It Is
• Risk Factors
• Signs and Symptoms
• How It Is Diagnosed
• What Affects the Outlook
• Treatment Approaches

What Is This Type of Cancer

Keratinising squamous cell carcinoma of the nasopharynx is a rare form of cancer that begins in the tissue lining the upper throat. The nasopharynx is the area that connects the back of your nose to the back of your mouth, located just above the roof of your mouth at the base of your skull^[1]. When you breathe through your nose, air flows through this area before reaching your lungs.

This type of cancer is classified by the World Health Organization as WHO type 1 nasopharyngeal carcinoma. The term “keratinising” refers to the presence of keratin in the cancer cells^[1]. Keratin is a protein naturally found in your hair and nails. In keratinising cells, this protein hardens the outermost layer of the tumour^[4].

Where It Develops

The nasopharynx has a box-like shape with several key features. The lateral walls are formed by the eustachian tube (which connects to the ear) and the fossa of Rosenmuller^[6]. The fossa of Rosenmuller is the most common place where nasopharyngeal cancer originates, accounting for 50 percent of all cases^[3].

The nasopharynx borders several important structures. At the front, it connects to the nasal cavity. At the back, it is formed by the muscles of the throat wall. The roof slopes downward and sits beneath the base of the skull, while the bottom is defined by the soft palate^[6].

How It Differs From Other Types

According to the World Health Organization, there are three main types of nasopharyngeal carcinoma, each classified by how the cancer cells appear under a microscope^[1].

Keratinising squamous cell carcinoma (WHO type 1) is one of these types, where cancer cells in the tissue lining the nasopharynx are covered with keratin^[1]. This type accounts for less than 20 percent of cases in the United States^[6]. It is the most common type in areas with low rates of nasopharyngeal cancer and is typically found in older adults^[9].

The other two types are both nonkeratinising, meaning hardening of the cells does not happen^[4]. Nonkeratinising squamous cell carcinoma (WHO type 2) includes cancer cells that are not covered with keratin. Undifferentiated or poorly differentiated carcinoma (WHO type 3) includes cancer cells that look very different from healthy cells when viewed under a microscope and tend to grow and spread very quickly^[1].

How Common It Is

Nasopharyngeal cancer is rare in the United States, affecting only about 1 out of 100,000 people each year^[1]. However, keratinising squamous cell carcinoma is less common than the nonkeratinising types^[8].

Nasopharyngeal cancer is more common in certain regions of the world, particularly in Southeast Asia, southern China, North Africa, and the Middle East^[1]. In the United States, it typically affects people ages 15 to 24 and ages 65 to 79^[1]. The disease occurs more often in males than in females^[6].

Risk Factors

The exact cause of keratinising squamous cell carcinoma of the nasopharynx is not fully understood. However, certain factors can increase the chance of developing this specific type of cancer.

The risk factors for keratinising squamous cell carcinoma (WHO type 1) are different from those for the nonkeratinising types. Heavy alcohol intake is one significant risk factor^[6]. A history of smoking or using any tobacco product also increases the risk^[6].

Unlike the nonkeratinising types, keratinising squamous cell carcinoma is not typically associated with the Epstein-Barr virus (EBV)^[8]. It usually develops in people over the age of 40^[8].

Signs and Symptoms

The most common symptom of nasopharyngeal cancer is a painless lump on the back of the neck^[1]. There may be one or multiple lumps. These masses appear when cancer spreads to the lymph nodes in your neck and causes them to swell^[1]. Lymph nodes are small glands that are part of the immune system and can be found throughout the body.

Other warning signs can affect the ears. These include tinnitus, or ringing in the ears, hearing loss, a feeling of fullness in the ears, and ear infections that do not go away^[1]. If an adult has an ear infection without an upper respiratory tract infection, an examination of the nasopharynx should be done^[7].

Additional symptoms may include headaches, stuffy nose on one side, nosebleeds, difficulty opening the mouth, facial pain, facial numbness (especially in the lower part of the face), and difficulty breathing or speaking^[1].

Many nasopharyngeal cancer symptoms are similar to symptoms of other, less serious illnesses. Having one or more of these symptoms does not mean you have cancer. However, you should talk to a healthcare provider if you have symptoms that last for more than two weeks or they keep coming back^[1].

How It Is Diagnosed

Diagnosis often begins with a physical exam. A healthcare professional may do a careful visual examination of your mouth, nose and throat, and may feel your neck for swelling in the lymph nodes^[6].

A procedure called a nasal endoscopy is commonly used when nasopharyngeal cancer is suspected^[1]. This test uses a thin, flexible tube with a tiny camera on the end, called an endoscope. The endoscope can go through your nose or through the opening in the back of your throat to allow the healthcare professional to see inside your nasopharynx.

If a suspicious area is found, a biopsy is performed. A biopsy is a procedure to remove a sample of tissue for testing in a laboratory^[6]. For nasopharyngeal cancer, the healthcare professional might take the sample during the nasal endoscopy procedure using special tools passed through the endoscope. If there is swelling in the lymph nodes in the neck, a needle might be used to draw out some cells for testing^[1].

A pathologist (a doctor who specializes in examining tissue) will examine the tissue under a microscope to determine the type of cancer. The presence of keratin in the cancer cells identifies keratinising squamous cell carcinoma.

Once the diagnosis is confirmed, additional tests help determine the extent of the cancer. These may include imaging tests such as CT scans (computed tomography), MRI scans (magnetic resonance imaging), PET scans (positron emission tomography), or X-rays^[1].

What Affects the Outlook

Several factors influence the outlook for people with keratinising squamous cell carcinoma of the nasopharynx. The presence or absence of keratin in the cancer cells can help predict how the cancer will respond to treatment^[14].

Research has shown that patients with keratinising squamous cell cancers had a higher incidence of locally advanced tumours compared to those with nonkeratinising types^[14]. However, they had a lower incidence of lymph node involvement at the time of diagnosis^[14].

The stage of the cancer is one of the most important factors affecting prognosis. The lower the stage, the better the outlook^[20]. Other factors include the size of the tumour, whether cancer has spread to lymph nodes, the specific location and extent of spread, age, and overall health^[20].

Smaller tumours (less than 2 centimeters) have a better outlook than larger tumours^[20]. People who are under 60 tend to have a better outlook than people who are over 60^[20]. People who have other health problems, such as heart or lung disease, may have a poorer outlook^[20].

Treatment Approaches

Treatment for keratinising squamous cell carcinoma of the nasopharynx depends on several factors, including the stage of the cancer, its size, and the person’s overall health. The treatment is generally the same for all types of nasopharyngeal cancer, though the stage of the cancer is often more important than the type in determining the treatment plan^[9].

Medical therapy typically consists of radiation therapy and chemotherapy^[15]. Radiation therapy uses high-energy beams to kill cancer cells or stop them from growing. Chemotherapy uses drugs that work throughout the body to destroy cancer cells.

Studies have shown that concurrent treatment combining cisplatin (a chemotherapy drug), fluorouracil (another chemotherapy drug), and radiation therapy has improved survival rates^[15]. Other studies have used chemotherapy given before radiation therapy, which has shown improvement in controlling the cancer locally or preventing it from getting worse^[15].

Treatment may also involve supportive care to manage side effects. Anesthetic lozenges and sprays may help minimize mouth or throat pain during radiation therapy. Medications such as pilocarpine, with or without artificial saliva products like oral sprays or gels, may improve dry mouth caused by radiation^[15].

The treatment of nasopharyngeal cancer is highly complex because of the proximity of the nasopharynx to the skull base^[9]. An expert will likely recommend one or more treatments tailored to each person’s specific situation, which may include radiation therapy, chemotherapy, surgery, or immunotherapy (treatment that helps the immune system fight cancer)^[9].