To understand these cancers, it helps to know a little about the larynx and hypopharynx.
What is the larynx?
The larynx, often called the voice box, is one of the organs that helps us speak. 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. 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)
Cancer that starts in the larynx (laryngeal cancer) is treated differently based on which section it starts in.
Your larynx and vocal cords have several functions:
- The larynx produces sound for speaking. The vocal cords move and come together to change the sound and pitch of your voice.
- The larynx protects the airway during swallowing. The epiglottis and vocal cords close tightly when you swallow to keep food and saliva from entering your lungs.
- 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 throat (pharynx) that lies beside and behind the larynx. The hypopharynx is the entrance into the esophagus (the tube that connects the throat to the stomach). Food goes from the mouth and through the hypopharynx and esophagus, where it then passes 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. Both types of cancers are discussed in the same document because these 2 separate structures are so close to each other.
Squamous cell carcinomas
Almost all cancers in the larynx or hypopharynx develop from the thin, flat cells called squamous cells, which are in the epithelium, the inner layer lining 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. When seen under a microscope, these cells look abnormal but not quite like cancer cells. 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 epithelium lining the larynx or hypopharynx. They have not grown into deeper layers or spread to other parts of the body. CIS is the earliest form of cancer. Most of these early cancers can be cured, but if CIS is not treated, it can develop into an invasive squamous cell cancer that will destroy the nearby tissues and can spread to other parts of the body.
Other cancers
Other rare types of cancer can also start in the larynx or hypopharynx.
Minor salivary gland cancers: Some areas of the larynx and hypopharynx have tiny glands known as minor salivary glands beneath their lining layer, 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 can have the following names:
- Adenocarcinoma
- Adenoid cystic carcinoma
- Mucoepidermoid carcinoma
Sarcomas: The shape of the larynx and hypopharynx depends on a framework of connective tissues and cartilage. Cancers like chondrosarcomas or synovial sarcomas can develop from connective tissues of the larynx or hypopharynx, but this is extremely rare.
Melanomas: These cancers usually start in the skin, but in rare cases they can start on inner (mucosal) surfaces of the body, such as in the larynx or hypopharynx.
These rare cancers of the larynx or hypopharynx are not discussed further here. The rest of this information refers only to squamous cell cancer.
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