Head and Neck Cancer
What is cancer?
Cancer is a group of many related diseases that begin in cells, the body's
basic unit of life. Normally, cells grow and divide to form new cells in an
orderly way. They perform their functions for a while, and then they die.
Sometimes, however, cells do not die. Instead, they continue to divide and
create new cells that the body does not need. The extra cells form a mass of
tissue, called a growth or tumor. There are two types of tumors: benign and
malignant. Benign tumors are not cancer. They do not invade nearby tissue or
spread to other parts of the body. Malignant tumors are cancer. Their growth
invades normal structures near the tumor and spreads to other parts of the body.
Metastasis is the spread of cancer beyond one location in the body.
What kinds of cancers are considered cancers of the head and neck?
Most head and neck cancers begin in the cells that line the mucosal surfaces
in the head and neck area, e.g., mouth, nose, and throat. Mucosal surfaces are
moist tissues lining hollow organs and cavities of the body open to the
environment. Normal mucosal cells look like scales (squamous) under the
microscope, so head and neck cancers are often referred to as squamous cell
carcinomas. Some head and neck cancers begin in other types of cells. For
example, cancers that begin in glandular cells are called adenocarcinomas.
Cancers of the head and neck are further identified by the area in which they
begin:
- Oral cavity. The oral cavity includes the lips, the front two-thirds of the
tongue, the gingiva (gums), the buccal mucosa (lining inside the cheeks and
lips), the floor (bottom) of the mouth under the tongue, the hard palate (bony
top of the mouth), and the small area behind the wisdom teeth.
- Salivary glands. The salivary glands produce saliva, the fluid that keeps
mucosal surfaces in the mouth and throat moist. There are many salivary glands;
the major ones are in the floor of the mouth, and near the jawbone.
- Paranasal sinuses and nasal cavity. The paranasal sinuses are small hollow
spaces in the bones of the head surrounding the nose. The nasal cavity is the
hollow space inside the nose.
- Pharynx. The pharynx is a hollow tube about 5 inches long that starts
behind the nose and leads to the esophagus (the tube that goes to the stomach)
and the trachea (the tube that goes to the lungs). The pharynx has three parts:
- Nasopharynx. The nasopharynx, the upper part of the pharynx, is behind the
nose.
- Oropharynx. The oropharynx is the middle part of the pharynx. The
oropharynx includes the soft palate (the back of the mouth), the base of the
tongue, and the tonsils.
- Hypopharynx. The hypopharynx is the lower part of the pharynx.
- Larynx. The larynx, also called the voicebox, is a short passageway formed
by cartilage just below the pharynx in the neck. The larynx contains the vocal
cords. It also has a small piece of tissue, called the epiglottis, which moves
to cover the larynx to prevent food from entering the air passages.
- Lymph nodes in the upper part of the neck. Sometimes, squamous cancer cells
are found in the lymph nodes of the upper neck when there is no evidence of
cancer in other parts of the head and neck. When this happens, the cancer is
called metastatic squamous neck cancer with unknown (occult) primary.
Cancers of the brain, eye, and thyroid as well as those of the scalp, skin,
muscles, and bones of the head and neck are not usually grouped with cancers of
the head and neck.
Next: How common are head and neck cancers? »
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Head and Neck Cancer
Cancer »
Defining cancer
Cancer is a term used for diseases in which abnormal cells divide without
control and are able to invade other tissues. Cancer cells can spread to
other parts of the body through the blood and lymph systems.
Cancer is not just one disease but many diseases. There are more than 100
different types of cancer. Most cancers are named for the organ or type of cell
in which they start -- for example, cancer that begins in the colon is called
colon cancer; cancer that begins in basal cells of the skin is called basal cell
carcinoma.
Cancer types can be grouped into broader categories. The main categories of
cancer include:
- Carcinoma - cancer that begins in the skin or in tissues that line or cover
internal organs.
- Sarcoma - cancer that begins in bone, cartilage, fat, muscle,
blood vessels, or other connective or supportive tissue.
- Leukemia - cancer that sta...
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