Nasopharyngeal cancer

Definition

Nasopharyngeal cancer is an uncontrolled growth of cells that begins in the nasopharynx, the passageway at the back of the nose.

Description

The nasopharynx connects the nose (hence, naso) to the pharynx, the shared passageway for air and food at the back of the nose and mouth. Air moves through the pharynx on its way into and out of the trachea, the tube that carries air to the lungs. Food passes through the pharynx on its way to the esophagus, the muscular tube that carries food to the stomach.

Although it is possible for people to breathe through the mouth, breathing through the nose is better. The nose warms and moistens air, and the interior of the nose has hairs to filter particles from the air. Thus, any blockage, such as a tumor or cancer in the nasopharynx, interferes with normal breathing.

Not all tumors that grow in the nasopharynx are malignant. Many are benign, but the tumors still cause problems because they often grow into the vessels that supply blood to the nose. Malignant cancers in the nasopharynx grow from squamous, or flat, epithelial cells. Epithelial cells form body coverings, such as skin. Cancers that originate in epithelial cells are known as carcinomas.

Demographics

Nasopharyngeal cancer is rare in most parts of the world. The exception is in Southeast Asia, where there are as many as 40 new cases each year for every 100, 000 people. In other parts of the world, there are as few as one new case per year for every 100, 000 people. Men are at a greater risk than women. Although all age groups can be affected by this cancer, like many other cancers, people over the age of 40 tend to be more susceptible.

Causes and symptoms

Several factors put people at risk for nasopharyngeal cancer. One is an infection with a type of herpes virus called Epstein-Barr virus (EBV). Another factor is genetic make-up, or inherited DNA. Finally, anything that introduces radioactive elements into the diet or respiratory pathway increases the risk of developing this cancer.

In certain parts of China, the soil has a high concentration of uranium and thorium, which break down into radioactive elements such as radium and radon. The elements are taken up by trees, which are burned for wood and become airborne. They also dissolve in water, and fish and plants draw them up. The fish are eaten. Some of the plants are used for tea. The scenario seems to increase the risk of nasopharyngeal cancer, but the exact way in which it does is not known.

In all parts of the world, people who work in sawmills or with wood products have a higher likelihood of acquiring nasopharyngeal cancer. Sawdust or chemicals in the wood may contribute to its development.

Recently, E. Lopez-Lizarraga demonstrated that human papilloma virus (HPV) is often present in people who contract nasopharyngeal cancer. Neither this link nor the others cited show a precise cause and effect, however. Some of the links may mask true causes. For example, in the HPV study, subjects who had HPV infection also tended to have poor oral hygiene. And in the case of EBV, infection with the virus is so common that some researchers are now investigating whether there is a unique strain of the EBV that puts individuals at greater risk for nasopharyngeal cancer.

Symptoms of nasopharyngeal cancer include:

• lump in the nose or neck
• headaches
• ear pain
• numbness on the side of the face
• difficulty breathing
• difficulty speaking

Diagnosis

A physician examines the nasopharynx in various ways, usually starting with an instrument such as a nasoscope. The nasoscope allows a look at the inside of the nasal cavity. Palpating, or touching, lymph nodes in the neck to check for enlarged ones is also part of the examination.

If suspicious growths are found, a biopsy is done to take a tissue sample. Different types of biopsy can be used. An incision may be made to obtain tissue, or a needle with a small diameter may be inserted into a suspicious mass to obtain cells, especially if there is a lump in the neck.

Computed tomography (CT) and magnetic resonance imaging (MRI) scans are also used. They help determine whether the cancer has spread from the walls of the nasopharynx. MRI offers a good way to examine the tonsils and the back of the tongue, which are soft tissues. CT is used as a way of studying the jaw, which is bone.

Treatment team

Generally, physicians with special training in the organs of the nose and throat take initial responsibility for the care of a patient with nasopharyngeal cancer. They are called otolaryngologists, or occasionally, otorhinolaryngologists. Otolaryngologists are usually labeled ENT (for ear, nose, and throat) specialists. An ENT specializing in cancer will probably lead the team, accompanied by radiation therapists and oncologists.

Clinical staging, treatments, and prognosis

Stage I describes a cancer that has not spread. It is not in the lymph nodes and is localized in the nasopharynx. Stage II describes a larger cancer, one that affects more than half the area of the nasopharynx, that is not in the lymph nodes. Stage III nasopharyngeal cancer has spread beyond the nasopharynx; it might affect the oropharynx, the cavity at the back of the mouth, or part of the throat. Or, it might have spread to the lymph nodes. Stage IV involves one or more of the following indications:

• spread of cancer to a site near the original site, such as the bones and nerves of the head
• more than one lymph node with cancer
• spread to other parts of the body, such as the larynx, the trachea, the bronchi, the esophagus, or more distant points, such as the lungs

The outlook for recovery from nasopharyngeal cancer is better the earlier the stage in which the cancer is diagnosed. For stage I and stage II, radiation or chemotherapy treatment of the affected area is sometimes all that is required to halt the cell growth. Decisions about which method to use depend on many factors, but the tolerance a patient has for radiation or chemotherapy and the size of the tumor are important.

Often, the most promising treatment option for a person with nasopharyngeal cancer is a clinical trial. The outlook for early stage diagnoses of nasopharyngeal cancer is good. The five-year survival rate is over 80% for small cancers, which are typically in Stage I. Cancers that are larger, but have not spread to the lymph nodes, usually have survival rate of 50% or more. Unfortunately, about half of all people diagnosed with nasopharyngeal cancer are not diagnosed until the cancer is advanced, which leads to a poorer prognosis.

Coping with cancer treatment

The patient should be an active member of the treatment team, listening to information and making decisions about which course of treatment to take. Premier cancer centers encourage such a role.

Appetite might be affected before, during, and after treatment. Before treatment, the presence of a tumor can interfere with chewing and swallowing food, and food might not seem as appealing as it once did. During treatment, particularly radiation treatment, the treated nasopharynx will be sore, and eating and breathing may be difficult.

Patients should also seek out a support network to help them cope with the psychological implications of cancer. In addition to family and friends, local support organizations can offer guidance, answer questions, and link newly diagnosed patients with others who have survived a similar experience.

Alternative and complementary therapies

Any technique, such as yoga, meditation, or biofeedback, that helps a patient cope with anxiety over the condition and discomfort from treatment is useful and should be explored as an option. Many herbal remedies are available to ease the symptoms of nausea that accompany treatment; the physician, however, should be notified of any remedies, herbal or otherwise, that are taken.

Clinical trials

There are a number of clinical trials currently in progress, especially with biological response modifiers (BMR), or substances that take advantage of the capabilities of the body's own immune system. Aldesleukin is one BMR that has been used to fight nasopharyngeal cancer, with inconclusive results. The Cancer Information Service at the National Institutes of Health offers information about clinical trials that are looking for volunteers. The service offers a toll-free number at (800) 422-6237.

Prevention

The link between HPV and nasopharyngeal cancer suggests that any precaution taken to avoid contracting sexually transmitted diseases, such as the use of condoms, affords protection. Radon gas levels should be checked in homes, and measures taken to reduce them if they are high. Individuals working with wood, especially those exposed to sawdust and chemicals, should wear protective respiratory covers, such as a breathing mask.

Special concerns

Additional cancers that begin in the nasopharynx can start in the lymph cells found there. Because of their origin, these cancers are called lymphomas.

See Also Oral cancer; Oropharyngeal cancer

Resources

PERIODICALS

Lopez-Lizarraga, E., et al. "Human Papilloma Virus in Tonsil-lar and Nasopharyngeal Carcinoma: Isolation of HPV Subtype 31." Ear, Nose, and Throat Journal 79 (December 2000): 942-4.

ORGANIZATIONS

SPOHNC, Support for People with Oral and Head and Neck Cancer. P.O. Box 53, Locust Valley, NY 11560-0053. (800) 377-0928. <http://www.spohnc.org>.

OTHER

Oral Cavity and Pharyngeal Cancer Online text. American Cancer Society. 22 May 2000. 6 July 2001 <http://www3.cancer.org>.

Diane M. Calabrese

KEY TERMS

Biopsy

—A diagnostic procedure in which a tissue sample is removed from the body for examination.

Computed tomography (CT)

—A radiographic technique in which multiple x-ray images assembled by a computer to give a three-dimensional image of a structure.

Endoscope

—Instrument designed to allow direct visual inspection of body cavities, a sort of microscope in a long access tube.

Magnetic resonance imaging (MRI)

—Magnetic fields and radio frequency waves are used to image internal structures of the body.

Nasoscope

—A type of endoscope designed specifically to be inserted through the nose and used for examination of the nasal cavity.

QUESTIONS TO ASK THE DOCTOR

• In what stage is this cancer?
• What is the outlook for a patient with my profile?
• What are the side effects of the treatments that are recommended? Which treatment gives the best combination of survival and quality of life?
• Is there a clinical trial for which I am eligible?