What are oral and oropharyngeal cancers?

Risk factors: Risk factors include cigarette smoking, chewing
tobacco, excessive alcohol intake, and infection with human
papillomavirus (HPV) or Epstein-Barr
virus (EBV). Infection with HPV has been linked to one in
five esophageal squamous cell carcinomas. Gastroesophageal reflux
disease (GERD), in which stomach acids enter the esophagus
and destroy the esophageal lining, can contribute to the risk of pharyngeal
cancer.

Etiology and the disease process: Oral and oropharyngeal cancers
appear to be caused by deoxyribonucleic acid (DNA) damage in the cells in the
mouth and throat. This DNA damage can occur from cigarette smoking, tobacco
chewing, or excessive alcohol intake. Most oral and oropharyngeal cancers are
carcinomas of the squamous cells, the flat cells that make up the mucosal
epithelium, the layer of cells lining the inside of the
mouth, nose, larynx, and throat. Less common are lymphomas, lymphoepitheliomas,
and minor salivary gland carcinomas. A rare type of oral cancer is verrucous
carcinoma, which usually does not metastasize but can penetrate deeply into nearby
tissue.

Incidence: According to the American Cancer Society, there were
approximately 36,450 new cases of oral and oropharyngeal cancer in 2010 in the
United States. The incidence is higher in men than in women. Persons over the age
of fifty years old are most likely to be affected, and the median age at diagnosis
occurs in the early sixties. Oropharyngeal cancer is still a relatively rare type
of cancer, and death rates due to oral and oropharyngeal cancers have been
decreasing since 1975.

Symptoms: Symptoms of oral and oropharyngeal cancer include lumps of
white, red, or dark patches inside the mouth that do not recede with time; mouth
sores that do not heal or that enlarge over time; lumps in the neck; persistent
pain in the mouth or tongue; thickening of the cheek; swelling or pain in the jaw;
soreness in the throat or a feeling that something is caught in the throat;
difficulty swallowing; difficulty chewing or moving the tongue (late-stage
symptom); difficulty moving the jaw (late-stage symptom); pain around the teeth;
loosening of the teeth not associated with periodontal disease; poorly fitting
dentures; numbness of the tongue or mouth; and hoarseness or changes in the
voice.

Screening and diagnosis: Frequent oral examinations are the best way
to detect signs of oral and throat cancer. Clinical suspicion of head and neck
cancer is based on the presence of any of the above symptoms for more than three
weeks. When a tumor is detected, it is graded or staged to determine how benign or
aggressive it is. The TNM (tumor/lymph node/metastasis) staging system is a
standard way of classifying tumors. T stands for the size of the primary tumor and
which tissues of the oral cavity or oropharynx the tumor has spread to, if any. N
refers to the extent of spread to regional lymph nodes. M is used to denote
whether the tumor has metastasized to distant organs. The most common metastatic
site is the lungs, followed by the liver and the bones. Within each of these
designations, there are several subcategories.

Following TNM staging, the tumor is classified as Stage 0, I, II, III, or IV.
Stage 0 refers to a tumor that is confined to the outer layer of oral or
oropharyngeal tissue and has not penetrated deeper or metastasized. Stage I tumors
are less than 2 centimeters (cm) in their greatest dimension and have not
metastasized. Stage II tumors are between 2 cm and 4 cm in greatest dimension and
have not metastasized. Stage III tumors are larger than 4 cm in diameter and have
not metastasized, although they may have invaded one of the nearby lymph nodes.
Stage IV is further divided into three substages: Stage IVA, in which tumors have
spread to nearby sites and may or may not have invaded one or more nearby lymph
nodes, Stage IVB, in which tumors may or may not have spread to nearby sites but
have spread to one or more lymph nodes, and Stage IVC, in which tumors have
metastasized to distant organs.

Treatment and therapy: The specific treatment varies based on the
location and stage of the cancer. Primary care physicians will refer patients to
specialists, including oral and maxillofacial surgeons, otolaryngologists (ear,
nose, and throat doctors), medical oncologists, radiation oncologists, and plastic
surgeons. At specialized cancer treatment facilities, several of these specialists
often work together to provide tailored care for patients. Treatment options
include radiation therapy, oral chemotherapy, and surgery, as well as combinations
of these treatments. The most commonly used treatment is a combination of
radiation therapy and chemotherapy with the drug cisplatin. In some cases, surgery
may be necessary to remove the cancer cells from a localized region. The surgery
is often followed by radiation therapy to destroy any remaining cancer cells.
Chemotherapy is sometimes given before other treatments to potentially enhance
effectiveness of the follow-up treatment. In addition, treatments for symptoms and
the side effects of therapies are often administered concomitantly.

Radiation therapy can take the form of external radiation from specialized
equipment or internal radiation, when radioactive substances are placed in seeds,
needles, or plastic tubes and inserted in the tissue. The preferred method of
delivery for radiation therapy, intensity-modulated radiotherapy,
focuses radiation to more selectively kill the tumor instead of the surrounding
healthy tissue. Surgery can be performed to remove tumors in the mouth or throat,
or lymph nodes in the neck.

In addition to radiation, chemotherapy, and surgery, targeted therapies are
also available. For patients with advanced cancer who cannot tolerate
chemoradiation, cetuximab (Erbitux) in combination with radiation therapy and
additional surgical consideration may be used. Cetuximab is a monoclonal antibody directed at a
protein that is abundant on cancer cells in this region.

Before starting any treatment, it is important for patients to ask their physicians about the treatment length and procedure, risks, side effects, and the results that may be expected.

Prognosis, prevention, and outcomes: The prognosis is good if
detected and treated early. However, many oral and throat cancers are not
diagnosed until they are late stage, often because they may be painless at early
stages or cause minor pains similar to a toothache. The stage of cancer will also
determine the type of treatment to use. After treatment, the cancer may reappear
(recur or relapse). The recurrence can occur in the mouth or throat (local
recurrence), in the lymph nodes (regional relapse), or in a distant site in the
body, often the lungs (distant recurrence). A relapse is associated with a poorer
prognosis. The five-year relative survival rate is a statistic that calculates the
survival of cancer patients relative to the expected survival for people without
cancer. This statistic can be used as a guide, but other factors, such as age,
health, and tumor properties, must be considered before arriving at a complete
prognosis. By studying patients treated between 1985 and 1991, the five-year
relative survival rate for oral cavity cancer was calculated to range from 83
percent for Stage I cancer to 47 percent for Stage IV tumors. The one-year
survival rate for all stages was 84 percent. The five-year relative survival rate
for oropharyngeal cancer ranges from 57 percent for Stage I cancer to 30 percent
for Stage IV cancer.

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