Laryngeal cancer affects the larynx, which is often called the "voice box" because it contains your vocal cords. Hypopharyngeal cancer affects the hypopharynx, which is the part of the esophagus (also known as “food pipe”) that lies beside and behind the larynx. Cancers of these 2 separate structures are discussed in the same document because they are so close to each other.

As shown in the picture below, the larynx is seen on the front of your neck as the "Adam's apple."
It is divided into 3 sections:

• the glottis (or the vocal cords) 
• the supraglottis (the area above the vocal cords, including the epiglottis, which closes off the larynx when you swallow to keep food from going into your lung) 
• 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" (trachea) and are 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.

Your hypopharynx is the part of the esophagus, or food pipe that lies beside and behind the larynx. The hypopharynx is the entrance into the esophagus. Food goes through the hypopharynx into the 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.

Almost all of the cancers of the larynx and hypopharynx develop from the thin, flat cells (called squamous cells) that form their lining layer (called epithelium). 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 never develops into actual cancer. It often goes away without any treatment, especially if the factors that cause pre-cancerous conditions and cancers (such as smoking) are stopped. (See the section "What Are the Risk Factors for Laryngeal and Hypopharyngeal Cancers?")

Some pre-cancerous conditions eventually develop into carcinoma in situ (CIS). In situ is a Latin term that means “in place.” CIS is the earliest form of cancer. With CIS, the cancer cells develop in the lining layer, but they do not invade deeper areas of the tissue or spread to other parts of the body. 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.

Some areas of the larynx and hypopharynx have tiny 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 have the following names:

• adenocarcinoma 
• adenoid cystic carcinoma 
• mucoepidermoid carcinoma