What is Oropharyngeal Cancer?
The oropharynx is part of the throat, located just behind the mouth, where the oral cavity ends. It includes the back third part of the tongue, the soft palate (the back part of the roof of the mouth), the tonsils, and the side and back walls of the throat. The oropharynx helps you to breathe, talk, eat, chew, and swallow. Minor salivary glands in the oropharynx keep your mouth moist with saliva, and help you digest food.
Oropharyngeal cancer is a type of throat cancer that develops in oropharynx. There are three main types of cancer found in the oropharynx: (1) soft palate cancer, (2) tongue base cancer, and (3) tonsil cancer.
Squamous Cell Carcinomas
More than 90% of oropharynx cancers begin in the flat, scale-like squamous cells that line the mouth and throat. Squamous cell cancer begins as a collection of abnormal (malignant) squamous cells. Most often, this cancer forms in older men who regularly use tobacco products and alcohol. More recently, it has been found in younger adults who have HPV (human papillomavirus), a sexually transmitted virus.
The earliest form of squamous cell cancer found is called carcinoma in situ. In this case, cancer cells are only found in the outer layer of epithelium cells. This form of cancer is easier to treat than invasive squamous cell carcinoma, which means that cancer has grown into deeper layers of the oropharynx.
Risk Factors & Symptoms
Following are common risk factors for the disease:
- Smoking and chewing tobacco
- Heavy alcohol use
- Being infected with Human Papillomavirus (HPV)
- A diet low in fruits and vegetables
- Drinking maté, a caffeine-rich drink common in South America
- Chewing betel quid, a type of chewing tobacco common in Asia
- A personal history of head and neck cancer
These and other symptoms may be caused by oropharyngeal cancer. Other conditions may cause the same symptoms. Consult a doctor if you have any of these problems:
- A sore throat that does not go away
- A dull pain behind the breastbone
- Trouble swallowing
- Weight loss for an unknown reason
- Ear pain
- A lump in the back of the mouth, throat, or neck
- A change in voice
Biomarker testing/Molecular testing of the tumor — Your doctor may want to test your tumor for P16 or HPV. In oropharyngeal squamous cell carcinomas, knowing this test result will help your doctor decide on the treatment that is best for you. The tumor may also be assessed for the Epstein-Barr Virus (EBV). This can cause cancers in the nasopharynx (upper part of the throat behind the nose).
If you are diagnosed with oropharyngeal cancer, the doctor needs to know the stage, or extent, of the disease to plan the best treatment. Staging is a careful attempt to find out whether the cancer has spread, and if so, to what parts of the body.
Oropharyngeal cancers are staged with the AJCC (American Joint Committee on Cancer) system. This is a rating system that assigns a measurement for TNM:
- T = Tumor characteristics, based on imaging tests. This describes how big the tumor is and how far into the oropharynx the cancer has grown.
- N = Lymph Nodes involved. This defines if and how cancer has spread to lymph nodes in the neck.
- M = Metastases. This explains if and where cancer has spread (into other organs, the chest, liver or bones).
Each of these factors are defined with a number ranging from 0 (or x – meaning it’s very early disease) to 4 a, b, c (meaning the disease is very advanced). After this, the cancer’s Stage is defined with a scale from “Stage 0” (for very early signs of cancer), to Stage IV a, b or c (for very advanced cancers).
Stage 0 (Carcinoma in Situ) - Abnormal cells are found in the lining of the oropharynx (T0). These abnormal cells may become cancer and spread into nearby normal tissue, but they haven’t (N0, M0).
Stage I - The cancer has formed and is two centimeters or smaller (T1). It is also only found in the oropharynx. No cancer is found in nearby lymph nodes (N0), or in other parts of the body (M0).
Stage II - The cancer is larger than two centimeters but not larger than four centimeters and is found in the oropharynx only (T2). Cancer is not found in lymph nodes (N0), and it has not spread to other parts of the body (M0).
Stage III - The cancer may be four centimeters or smaller (T1-T3). It is either large (spreading to the epiglottis) without spreading to lymph nodes; or it is smaller but has spread to one lymph node on the same side of the neck as the primary tumor (N1). The cancer has not spread to other parts of the body (M0)
Stage IV is divided into stage IVA, IVB and IVC as follows:
- Stage IVA: Cancer has spread beyond the oropharynx to the larynx, the roof of the mouth, the lower jaw, or muscles that move the tongue or support chewing, or to the epiglottis (T1 to T4a). Cancer may have spread to one or more lymph nodes but the lymph node is not larger than six centimeters (N0-N2). Cancer has not spread to other parts of the body.
- Stage IVB: The tumor can be any size. It may surround the carotid artery or spread to the muscle that opens the jaw, the bones that move the jaw, nasopharynx or base of the skull (any T). Cancer has not spread to other parts of the body (M0), but one or more lymph nodes are involved. Several lymph nodes can be any size, or one lymph node may be larger than six centimeters (any N).
- Stage IVC: The tumor may be any size and has spread beyond the oropharynx to other parts of the body (any T, any N, M1).
Surgery is a common treatment for oropharyngeal cancer. Cancers of the oropharynx often spread to the lymph nodes in the neck. Depending on the stage and exact location of the cancer, it may be necessary to remove these lymph nodes by an operation called a neck or lymph node dissection. There are several types of neck dissection procedures, and they differ in how much tissue is removed from the neck.
- Partial or selective neck dissection - Only a few lymph nodes are removed.
- Modified radical neck dissection - Most lymph nodes on one side of the neck between the jaw bone and collarbone and some muscle and nerve tissue are removed.
- Radical neck dissection - Nearly all nodes on one side and muscles, nerves and veins are removed.
The most common side effects of any neck dissection are numbness of the ear, weakness when raising the arm above the head, and weakness of the lower lip. These side effects are caused by injury during the operation to certain nerves that supply these areas.
After a selective neck dissection, weakness of the arm and lower lip usually go away after a few months. But if either nerve is removed as part of a radical neck dissection or because of involvement with tumor, the weakness will be permanent.
Cancers of the head and neck are treated by operations that remove part of the facial bone structure. The changes are visible. Recent advances in facial prostheses are now giving patients the ability to have a more normal look and also improve vocal clarity (another side effect of surgical treatments.)