Overview
Cancer of the throat is one of many head and neck cancers. The throat is a hollow tube about 5 inches long that starts behind the nose and roof of the mouth then merges into the windpipe and becomes the esophagus further down the neck.
The majority of throat cancers are related to tobacco and/or excessive alcohol exposure. However, in 25% of cases, cancer of the throat is not associated with any known risk factor. Recent research has raised the possibility of a connection between viral infection by the human papilloma virus (HPV) and cancer of the mouth and throat.
Treatment for patients with throat cancer is extremely variable and depends largely on the stage of disease. Surgery or radiation therapy is highly effective in the treatment of most early stage cancers. However, the advanced stages of cancer that involve lymph nodes in the neck are more difficult to treat. More than 70% of patients with throat cancer have advanced cancers at the time of initial diagnosis.
Because many throat cancers are already advanced at the time of diagnosis, it is highly recommended that patients be carefully evaluated in medical centers that treat many patients with throat cancer. Patients with throat cancer require a multidisciplinary team approach that is often only available at specialty medical centers. A multidisciplinary team may be comprised of a head and neck surgeon, a radiation oncologist, a medical oncologist, a pathologist, a dentist, and social services personnel. Evaluation by an experienced team is essential for determining optimal treatment.
Signs and Symptoms
The signs and symptoms of throat cancer can be quite variable. The most common symptoms are a persistent sore throat, trouble swallowing, a lump in the neck, a change in voice, or ear pain. The clinical appearance of throat cancer ranges from symptomatic white patches to large wounds. Cancer of the throat may be preceded by visible precursor lesions that are not yet malignant. These appear as heaped up cells or reddish sores.
Diagnostic Procedures
Proper diagnosis is important for assuring that the right treatment is selected for a certain cancer. Even when the primary cancer is obvious, a thorough examination is necessary because a second primary cancer is found in 10% to 15% of patients.
How throat cancer is identified depends on where the cancer is. Throat cancers in the upper part of the throat can be identified by looking into the mouth. Therefore, some throat cancers are initially detected by dentists. The lower part of the throat, however, is best observed using a thin-lighted tube called an endoscope. In addition to looking for the cancer visually, a doctor may perform a physical examination and feel the throat for lumps. Endoscopy under general anesthesia is often required to accurately determine whether there is a second cancer in nearby structures. The esophagus is the most frequent site of second primary cancers.
If abnormal tissue is found with any of these diagnostic techniques, the doctor will examine the cells more closely to determine if they are cancerous by performing a biopsy. In this procedure, a small piece of tissue is cut out and examined under a microscope.
Once the primary throat cancer is identified, the margins of the cancer are tattooed using ink in order to facilitate later surgical procedures. This step is particularly useful when neoadjuvant chemotherapy or radiation therapy is given to shrink the cancer before surgery.
Other techniques may be used to determine the extent to which the cancer has spread to lymph nodes. These techniques include computed tomographic (CT) scans, magnetic resonance imaging (MRI) scans, ultrasound, and positron emission tomography (PET) scans. However, often these tests substitute for lymph node dissection of the neck for detecting spread of cancer.
Cellular Classification
Throat cancer is classified based on the type of cells involved. Most throat cancers begin in the squamous cells that line the throat, and are thus called squamous cell cancers. Biopsy specimens may show the cancer to be noninvasive, in which case the term “carcinoma-in-situ” is applied.
The term “leukoplakia” refers to an unusual looking white patch of tissue that can be observed during an examination and cannot be rubbed off. Cells from this unusual tissue are collected and examined under a microscope to determine their origin. Leukoplakia can be caused several factors: (1) a heaped up surface layer of normal cells (hyperkeratosis); (2) an actual early invasive carcinoma, or (3) may represent only a fungal infection, lichen planus, or other benign oral disease.
Staging
Staging is the process of identifying how extensive the cancer is. Accurately identifying the stage of a cancer helps determine what treatments will be most effective. Staging is particularly important for determining whether a cancer has spread from its original site to other parts of the body. The four general cancer stages are early, locally advanced, metastatic, and recurrent.
Stage I, II, and some stage III cancers are referred to as early stage. At these stages, the cancer is small, localized and can typically be treated with surgery or radiation therapy.
Stage I The cancer is no more than 2 centimeters (about 1 inch) and has not spread to lymph nodes in the area.
Stage II The cancer is more than 2 centimeters, but less than 4 centimeters (less than 2 inches) and has not spread to lymph nodes in the area.
Stage III The cancer is considered “early” if it is small and the single involved node can be removed or irradiated with high probability of cure. Stage III cancers that are more extensive than this are considered locally advanced.
Some stage III and all stage IV cancers are referred to as locally advanced. These are large and/or have spread to regional lymph nodes.
Stage III The cancer is more than 4 centimeters, or it is any size with spread to only one lymph node on the same side of the neck as the primary cancer. The lymph node containing the cancer can measure no more than 3 centimeters (just over 1 inch).
Stage IV The cancer has spread to tissues around the lip and mouth. The lymph nodes may or may not contain cancer or the cancer is any size and has spread to more than one lymph node on the same side of the neck as the cancer, to lymph nodes on one or both sides of the neck or to any lymph node that measures more than 6 centimeters (over 2 inches).
Metastatic Cancer has spread to distant sites.
Recurrent Cancer has failed to respond completely to primary treatment or has recurred after a complete response.
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