What is Head and Neck Cancer

Executive Summary

Head and neck cancer is concerned with different types of cancerous growth that develop in the head and neck region. It occurs in the mouth, throat, tongue, larynx, pharynx, salivary glands, nose or sinuses. In situ, head and neck cancers are carcinoma if the cancer is only in the squamous cell layer. And if cancer moves into the deeper layers, it is invasive squamous cell carcinoma.

Head and neck cancers that start in glandular cells are adenocarcinoma, mucoepidermoid carcinoma or adenoid cystic carcinoma (ACC). Depending upon the region of occurrence, head and neck cancers are classified as oral cavity, salivary glands, Paranasal sinuses and nasal cavity, pharynx or throat (Nasopharynx, Oropharynx, and Hypopharynx), and larynx or voice box. Squamous cell carcinomas are usually in the lymph nodes in the upper part of the neck, with no evidence of cancer in any other part of the head and neck region, additionally, head and neck cancers are more prevalent in men than in women.

The different head and neck cancer types include hypopharyngeal cancer, laryngeal cancer, lip and oral cavity cancer, nasopharyngeal cancer, oropharyngeal cancer, and metastatic squamous neck cancer with occult primary, salivary gland cancer, paranasal sinus and nasal cavity cancer.

What Is Head and Neck Cancer?

Cancer starts when normal, healthy cells undergo change and grow uncontrollably, forming a mass of cells called tumors, additionally, a tumor growth can be benign or malignant. While, a benign tumor is a mild growth that does not spread or metastasize from the initial development area and a malignant tumor is an aggressive tumor that grows and spreads or metastasize to different parts of the body.

Head and neck cancer

Head and neck cancer is a broad term describing different types of cancerous growth that develop in the head and neck region additionally, these cancers can begin in the mouth, throat, tongue, larynx, pharynx, salivary glands, nose or sinuses ^​1​. Cancers of the head and neck region could be called squamous cell carcinoma, moreover, they usually begin in the squamous epithelium that lines the head and neck region’s tissue layers and mucosal surfaces ^​2​.

In situ, head and neck cancers are called carcinoma if the cancer growth has only been found in the squamous cell layer additionally, if cancer has moved into the deeper layers, the type is called an invasive squamous cell carcinoma. If doctors or specialists cannot identify the primary spot of cancer growth, it is called a cancer of unknown primary moreover, head and neck cancers that start in glandular cells like salivary glands are called adenocarcinoma, mucoepidermoid carcinoma or adenoid cystic carcinoma (ACC) ^​3​.

Classifications

Based on the area where they begin, head and neck cancers can be classified as follows:

Oral cavity: The oral cavity includes the lips, the front two-thirds of the tongue, the teeth, gums or gingiva, the lining inside the lip and cheeks (buccal mucosa), the floor or bottom mouth below the tongue, the hard palate (the bony top part of the mouth), and moreover, the tiny area of the gum behind the wisdom teeth (retromolar trigone).

Salivary glands: The salivary glands can be divided into major and minor and they are located in the ground or floor of the mouth, in front of the ears, under the jaw bone, other parts of the upper digestive tract, and also, throughout the mucous membranes of the mouth and throat. 

 Paranasal sinuses and nasal cavity: Paranasal sinuses refer to the tiny hollow spaces in the bones of the head surrounding the nose. The hollow space inside the nose is the nasal cavity.

Pharynx or throat: Pharynx is a hollow tube that starts behind the nose and leads to the esophagus and trachea. The esophagus is the tube that goes to the stomach, and the trachea is the tube that goes to the lungs.

The pharynx has three parts: 

1. Nasopharynx: refers to the upper part of the throat or pharynx, behind the nose.
2. Oropharynx: refers to the middle part of the throat or pharynx. The oropharynx includes the base of the tongue, tonsils and the soft palate (the back of the mouth).
3. Hypopharynx: it is the lower part of the throat or pharynx.
4. Larynx or Voice box: It’s a passageway by the cartilage just below the throat or pharynx in the neck. The structure contains the vocal cords additionally, larynx also includes a tiny piece of tissue called the epiglottis that moves to cover the larynx and it prevents food from entering the air passages.

Lymph nodes in the upper part of the neck

Sometimes, squamous cell carcinomas are found in the lymph nodes in the upper part of the neck, with no evidence of cancer in any other part of the head and neck region. and so, Cancer in such a case is called a metastatic squamous neck cancer with unseen (occult) primary.

We usually don’t consider cancerous growth in the eye, brain and thyroid as a type of head and neck cancer. Also, cancers of the scalp, bones, skin and muscles of the neck and head region aren’t included in this category.

Head and neck cancers are more prevalent in men than in women. Additionally, the upper aerodigestive tract cancers account for three percent of all cancer growths in the United States. 

Types of head and neck cancers

1. Hypopharyngeal Cancer
2. Laryngeal Cancer
3. Lip and Oral Cavity Cancer
4. Nasopharyngeal Cancer
5. Oropharyngeal Cancer
6. Metastatic Squamous Neck Cancer with Occult Primary
7. Salivary Gland Cancer
8. Paranasal Sinus and Nasal Cavity Cancer

References