What Are Laryngeal Cancer and Hypopharyngeal Cancer?

Laryngeal cancer starts in the larynx, an organ in the throat that contains the vocal cords and plays an important role in talking, eating, and breathing. Hypopharyngeal cancer starts in the hypopharynx, the lowest part of the pharynx. The pharynx is a hollow tube about 5 inches long that starts behind the nose and ends at the top of the trachea, or airway between the larynx and the lungs, and esophagus, or tube that connects the throat to the stomach. Laryngeal and hypopharyngeal cancers are also known as head and neck cancers.

Laryngeal and hypopharyngeal cancers begin when the cells in the larynx or hypopharynx grow and divide without stopping. These cells create lumps (masses) called tumors that can spread to other areas of the body and form new tumors.

About 12,250 people will be diagnosed with laryngeal cancer and 2,400 people will be diagnosed with hypopharyngeal cancer in the United States in 2008, according to the American Cancer Society. 

The Larynx and Pharynx

The larynx is often referred to as the “voice box” because it contains the vocal cords. This organ is shaped like a tube and is located at the top of the airway (trachea) between the larynx and the lungs. The larynx opens to let air pass into the lungs when you breathe and the vocal cords in the larynx vibrate to make the sounds you use to speak. The epiglottis at the top of the larynx is a flap that closes the larynx when you swallow. This stops food from getting into your lungs.

Cancer can start in any of the three parts of the larynx:

• Supraglottis - Section above the vocal cords that contains the epiglottis.
• Glottis - Section that holds the vocal cords.
• Subglottis - Section below the vocal cords that connects the larynx to the trachea.
  

About two-thirds of laryngeal cancers start in the glottis. Most of the rest start in the supraglottis and only 5 percent start in the subglottis or in two overlapping sections of the larynx.

The hypopharynx is the lower part of the pharynx (throat) and it surrounds the larynx. The pharynx is a hollow tube about 5 inches long that starts behind the nose and ends at the top of the trachea and esophagus (tube that connects the throat to the stomach). When you eat, the food travels from the hypopharynx into the esophagus. When you breathe, air goes through the pharynx and into the trachea.

How Laryngeal Cancer and Hypopharyngeal Cancer Start

A laryngeal or hypopharyngeal tumor is a growth of abnormal cells. These cells may be either noncancerous (benign) or cancerous (malignant). Benign laryngeal and hypopharyngeal tumors are made of abnormal cells that do not spread (metastasize) to other parts of the body. In contrast, the cells in cancerous laryngeal and hypopharyngeal tumors can metastasize, either by spreading directly to tissue or organs near the mouth and throat, or by traveling through the bloodstream or the lymph system (which helps drain fluid and waste from the body) to other parts of the body.

Almost all laryngeal and hypopharyngeal cancers start in the squamous cells in the throat. These flat cells line the inner walls of the larynx and pharynx and this type of cancer is known as squamous cell carcinoma. If cancer cells are found only in the lining of the larynx or hypopharynx, the tumor is known as carcinoma in situ. If the cancer cells have spread into deeper layers of the larynx or hypopharynx, the tumor is known as invasive squamous cell carcinoma.

When cancer spreads from its original place to another part of the body, the tumor that develops has the same kinds of cells and is called by the same name as the original tumor. For example, if laryngeal cancer spreads to the lungs (metastasizes), the cancer cells in the lungs are laryngeal cancer cells and the disease is metastatic laryngeal cancer, not lung cancer. This is important because metastatic laryngeal cancer is treated very differently from lung cancer.

Types of Laryngeal and Hypopharyngeal Cancers

The most common kind of laryngeal and hypopharyngeal cancer is squamous cell carcinoma.

• Squamous cell carcinoma - This type of cancer starts in the flat, scalelike cells that line the inner walls of the larynx and pharynx. More than 90 percent of cancers of the larynx and hypopharynx are squamous cell carcinomas.
• Verrucous carcinoma - This type of squamous cell carcinoma rarely spreads (metastasizes) from the larynx or hypopharynx to other parts of the body, but it can spread deeply into the tissue that surrounds the larynx or pharynx. About 5 percent of squamous cell carcinomas are verrucous carcinomas.
  

Other, much less common types of laryngeal and hypopharyngeal cancer are:

• Adenocarcinoma, adenoid cystic carcinoma, and mucoepidermoid carcinoma - These cancers start in the tiny glands under the layer of squamous cells in the larynx and hypopharynx. These glands make mucus and saliva to keep your throat moist.
• Sarcoma -  Cancerous sarcoma cells come from or resemble normal connective tissues, which support or connect different body parts and tissues. Certain types of sarcoma, such as chondrosarcoma and synovial sarcoma, can start in connective tissue in the larynx or hypopharynx.

Key Statistics

According to the American Cancer Society, cancers of the larynx and hypopharynx are much more common in men than in women; about 9,680 cases of laryngeal cancer and 1,900 cases of hypopharyngeal cancer are expected to be diagnosed in men in 2007, compared with 2,570 cases of laryngeal cancer and 500 of hypopharyngeal cancer in women.

This content has been reviewed and approved by Myo Thant, MD.