What are laryngeal and hypopharyngeal cancers?

What are laryngeal and hypopharyngeal cancers?
Laryngeal and hypopharyngeal cancers start in the lower part of the throat. Cancer starts when cells in the body begin to grow out of control. Almost any cell in the body can become cancerous and spread to other parts of the body. To learn more about the origin and spread of cancer, read What is cancer?

What is the larynx?
The larynx is the vocal cord, one of the organs that allow us to speak, since it contains the vocal cords. The larynx is located in the neck, above the opening of the trachea. There, it helps keep food and liquid from entering the windpipe. The larynx is divided into three parts:

The supraglottis is just over the vocal cords and contains the epiglottis, a flap of tissue that closes the larynx when swallowing. Its job is to send food down the esophagus (the tube that connects to the stomach), and prevent food and liquid from going into your lungs.
The glottis contains the vocal cords.
The subglottis is located below the vocal cords.
Cancer that begins in the larynx (larynx cancer) is treated according to the section where it originates.

Your larynx and vocal cords have several functions:
The larynx produces the sound of speech. The vocal cords move and come together to cause a change in the sound and pitch of your voice.
The larynx protects your airways when you swallow. The epiglottis and vocal cords close tightly when you swallow to prevent food and liquid from getting into your lungs.
The vocal cords open naturally when you breathe so that air can move in and out of your lungs.
What is the hypopharynx?
The hypopharynx is the part of the throat (pharynx) that lies next to and behind the larynx. This is the access to the esophagus (the tube that connects the throat to the stomach). When you swallow food and liquid, it passes through your mouth and throat through the hypopharynx and esophagus, and then into your stomach. The hypopharynx helps ensure that food goes around the larynx and into the esophagus.

Laryngeal and hypopharyngeal cancers
Cancer that starts in the larynx is called laryngeal cancer, while cancer that starts in the hypopharynx is called hypopharyngeal cancer. Both types of cancer are discussed in this article due to the close proximity of these two structures.

Squamous cell carcinomas
Almost all cancers of the larynx or hypopharynx develop from thin, flat cells called squamous cells that are found in the epithelium, the innermost layer that lines these two structures. Cancer that starts in this layer is known as carcinoma or squamous cell cancer .

Most cases of squamous cell cancer of the larynx and hypopharynx begin as a pre-cancer, called dysplasia. When viewed under a microscope, these cells look abnormal, but not as abnormal as cancer cells. In most cases, dysplasia does not turn into cancer. They usually go away without treatment, especially if the underlying cause (such as smoking) is removed. (See Risk factors for laryngeal and hypopharyngeal cancers .) Most laryngeal and hypopharyngeal precancers do not cause problems unless they arise on the vocal cords.

Sometimes the dysplasia will progress to carcinoma in situ or CIS. Carcinoma in situ is the earliest form of cancer. In CIS, cancer cells are seen only in the epithelium lining the larynx or hypopharynx. These cells have not invaded the deeper layers or spread to other parts of the body.Most of these early cancers can be cured, but if carcinoma in situ is not treated, it can develop into an invasive squamous cell cancer that will destroy nearby tissue and spread to other parts of the body.

Other types of cancer
Other rare cancers can also start in the larynx or hypopharynx.

Minor salivary gland cancers: Some parts of the larynx and hypopharynx have tiny glands under their lining layer, called minor salivary glands. These glands produce mucus and saliva to lubricate and moisten the area. Cancer rarely develops in the cells of these glands.

Sarcomas: The shape of the larynx and hypopharynx depends on a framework of connective tissues and cartilage. Cancers such as chondrosarcomas or synovial sarcomas can originate from the connective tissues of the larynx or hypopharynx, but these are very rare.

Melanomas: These cancers usually start in the skin, but rarely can start on the innermost (mucosal) surfaces of the body, such as the larynx or hypopharynx.