What is the larynx?

The larynx, often called the "voice box," is one of the organs responsible for speech. It contains the vocal cords. It is located in the neck, at the opening of the trachea (windpipe). There, it helps protect the trachea from food and fluids. From the outside, the larynx can be seen on the front of your neck as the "Adam's apple." It is divided into 3 sections:

• the supraglottis (the area above the vocal cords); it contains the epiglottis, which closes off the larynx when you swallow to keep food from going into your lungs

• the glottis (the area containing the vocal cords)

• the subglottis (the area below the vocal cords)

Knowing these 3 different sections is important because the cancer is treated differently depending on where it starts.

Your larynx and vocal cords sit above your windpipe at the entrance into your lungs. They have several functions:

• The larynx produces sound for speaking.

• The larynx protects the airway during swallowing.

• The vocal cords come together to change the sound and pitch of your voice. They close tightly when you swallow to keep food and saliva from entering your lungs and causing pneumonia or blockage of breathing tubes.

• The vocal cords open naturally when you breathe so that air can get in and out of your lungs.

What is the hypopharynx?

The hypopharynx is the part of the esophagus (food pipe) that lies beside and behind the larynx. The hypopharynx is the entrance into the esophagus. Food goes from the mouth and through the hypopharynx and esophagus where it then passes through the neck and chest into the stomach. The structure of the hypopharynx makes sure that food goes around the larynx and into the esophagus.

Cancers of the larynx and hypopharynx

Cancers that start in the larynx are called laryngeal cancers; cancers of the hypopharynx are called hypopharyngeal cancers. Cancers of these 2 separate structures are discussed in the same document because they are so close to each other.

Squamous cell carcinomas

Almost all of these cancers develop from the thin, flat cells (called squamous cells) that form the lining layer (called epithelium) of these 2 structures. Cancer beginning in this layer of cells is called squamous cell carcinoma or squamous cell cancer. Most squamous cell cancers of the larynx and hypopharynx begin as pre-cancerous conditions called dysplasia. Most of the time, dysplasia doesn't turn into actual cancer. It often goes away without any treatment, especially if the underlying cause (like smoking) is stopped. (See the section, "What are the risk factors for laryngeal and hypopharyngeal cancers?")

Some cases of dysplasia will progress into a condition called carcinoma in situ (CIS). In CIS, the cancer cells are only seen in the layer lining the larynx or hypopharynx. They have not grown into deeper areas of the tissue or spread to other parts of the body. CIS is the earliest form of cancer. Most of these early cancers can be cured. The usual treatment is to strip (cut away) the lining layer or destroy it with a laser beam. If CIS is not treated, most will develop into an invasive squamous cell cancer that will destroy the nearby tissues and spread to other parts of the body.

Other cancers

Some areas of the larynx and hypopharynx have tiny glands beneath their lining layer, known as minor salivary glands. These glands produce mucus and saliva to lubricate and moisten the area. Cancer rarely develops from the cells of these glands, but when it does, these cancers have the following names:

• adenocarcinoma
• adenoid cystic carcinoma
• mucoepidermoid carcinoma

These cancers are distinguished from squamous cell cancer and from one another by the kinds of cells they are made of and by the way these cells are arranged.

The shape of the larynx and hypopharynx depends on a framework of connective tissues and cartilage. Cancers such as chondrosarcomas or synovial sarcomas can develop from connective tissues of the larynx or hypopharynx, but this is extremely rare.

Because cancers forming in glands and connective tissues of the larynx or hypopharynx are so rare, they are not discussed further in this document.

The following information refers only to squamous cell cancer.

Last Medical Review: 05/07/2009
Last Revised: 05/07/2009