Head and neck cancer

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**Head and neck cancer**
*Classifications and external resources*
ICD-10	C07-C14, C32, C33

Head and neck cancers are malignant growths originating in the lip and oral cavity (mouth), nasal cavity, pharynx, larynx, thyroid, paranasal sinuses, salivary glands and cervical lymph nodes of the neck. Head and neck cancers are most commonly squamous cell carcinomas, originating from the squamous cells that line the upper aerodigestive tract.

Head and neck cancer poses a serious health risk, with the American Cancer Society projecting that approximately 36,500 new cases of head and neck cancer will be diagnosed in the United States and that 11,000 American deaths will result from head and neck malignancies in 2003. While head and neck cancer accounts for only 3% of all new cancer cases and 2% of all cancer deaths in the United States annually, it is the fifth most common malignancy worldwide. In Southeast China and Taiwan, head and neck cancer, specifically Nasopharyngeal Cancer is the most common cause of death in young men.

Tobacco and alcohol are the primary etiologic agents in most head and neck cancers, suggesting prevention should be a primary public health goal in the field. Emerging evidence suggests that inherited factors and exposure to other agents play important roles, and these may help refine prevention strategies. Nearly identical percentages are reported from Britain, but head and neck cancers have a much greater impact in certain other parts of the world, especially where tobacco and/or betel nut chewing is common, and are the leading causes of cancer mortality worldwide. Despite improvements in diagnosis and local management, long-term survival rates in head and neck cancer have not increased significantly over the past 40 years and are among the lowest worldwide of the major cancers. The problem is even worse for select populations such as African Americans, for whom survival rates have actually decreased. Oropharyngeal cancer, the largest subgroup of head and neck cancers, has a 5-year relative survival rate of only 59% for United States whites and 35% for blacks. Although early-stage head and neck cancers (especially laryngeal and oral cavity) have high cure rates, over 60% of head and neck cancer patients present with advanced disease. Cure rates decrease in locally advanced cases, whose probability of cure is inversely related to tumor size and even more so to the extent of regional node involvement.

Survival advantages provided by new treatment modalities have been undermined by the significant percentage of patients cured of head and neck squamous cell carcinoma (HNSCC) who subsequently develop second primary tumors. Second primaries are the major threat to long-term survival after successful therapy of early-stage HNSCC. Their high incidence results from the same carcinogenic exposure responsible for the initial primary process, called field cancerization. In addition to the problem of long-term survival in the face of second primary risk, HNSCC patients also face tremendous impacts on quality of life after definitive therapy. Despite marked advances in reconstructive surgery and rehabilitation, intensity-modulated radiotherapy (IMRT) and conservation approaches to certain malignancies, some patients continue to have significant functional deficits.

1 Introduction
2 Incidence and Epidemiology
3 Etiology and Genetics
4 Head and Neck Cancer Treatment
5 See also
6 External links

[edit] Introduction

Epithelial carcinomas of the head and neck arise from the mucosal surfaces in the head and neck area and typically are squamous cell in origin. This category includes tumors of the paranasal sinuses, the oral cavity, and the nasopharynx, oropharynx, hypopharynx, and larynx. Tumors of the salivary glands differ from the more common carcinomas of the head and neck in etiology, histopathology, clinical presentation, and therapy. Less frequently, tumours may arise from the salivary glands, and in the paranasal sinuses.

[edit] Incidence and Epidemiology

The number of new cases of head and neck cancers in the United States was 38,530 in 2004, accounting for about 3% of adult malignancies. The worldwide incidence exceeds half a million cases annually. In North America and Europe, the tumors usually arise from the oral cavity, oropharynx, or larynx, whereas nasopharyngeal cancer is more common in the Mediterranean countries and in the Far East.

[edit] Etiology and Genetics

Alcohol and tobacco use are the most common risk factors for head and neck cancer in the United States. Smokeless tobacco is an etiologic agent for oral cancers. Other potential carcinogens include marijuana and occupational exposures such as nickel refining, exposure to textile fibers, and woodworking.

Dietary factors may contribute. The incidence of head and neck cancer is highest in people with the lowest consumption of fruits and vegetables. Certain vitamins, including dietary carotenoids, may be protective; retinoids are being tested for prevention.

Some head and neck cancers may have a viral etiology. The DNA of human papillomavirus has been detected in the tissue of oral and tonsil cancers, and may predispose to oral cancer in the absence of tobacco and alcohol use. Epstein-Barr virus (EBV) infection is associated with nasopharyngeal cancer. Nasopharyngeal cancer occurs endemically in some countries of the Mediterranean and Far East, where EBV antibody titers can be measured to screen high-risk populations. Nasopharyngeal cancer has also been associated with consumption of salted fish, which may contain high levels of nitrites.

[edit] Head and Neck Cancer Treatment

After a histologic diagnosis has been established and tumor extent determined, the selection of appropriate treatment for a specific cancer depends on a complex array of variables, including tumor site, relative morbidity of various treatment options, patient performance and nutritional status, concomitant health problems, social and logistic factors, therapy anticipated for potential recurrences or second primaries, and patient preference.

Several generalizations are useful in therapeutic decision making, but variations on these themes are numerous. Surgical resection and radiation therapy are the mainstays of treatment for most head and neck cancers and remain the standard of care in most cases. For small primary cancers without regional metastases (stage I or II), wide surgical excision alone or curative radiation therapy alone is used. For more extensive primary tumors or for those with regional metastases (stage III or IV), planned combinations of pre- or postoperative radiation and complete surgical excision are generally used. More recently, as historical survival and control rates are recognized as less than satisfactory, there has been an emphasis on the use of various induction or concomitant chemotherapy regimens.

Patients with head and neck cancer can be categorized into three clinical groups: those with localized disease, those with locally or regionally advanced disease, and those with recurrent and/or metastatic disease. Comorbidities associated with tobacco and alcohol abuse can affect treatment outcome.

(C07-C08) The salivary glands give rise to a variety of uncommon tumours including adenocarcinomas, pleomorphic adenomas, and adenoid cystic carcinomas.
The term throat cancer is sometimes used as a layman's term for a cancer of the larynx or pharynx, a cancer that has metastasized to the lymph nodes of the neck, or even esophageal cancer.
- (C33) Cancer of the trachea is a rare cancer that may also be considered throat cancer.
(C32) Laryngeal cancer begins in the larynx, the part of the throat that contains the vocal cords and is used for breathing, swallowing, and talking.
(C10) Oropharyngeal cancer begins in the oropharynx, the middle part of the throat that includes the soft palate, the base of the tongue, and the tonsils.
(C11) Nasopharyngeal cancer begins in the nasopharynx, the upper part of the throat behind the nose.
(C13) Hypopharyngeal cancer begins in the hypopharynx, the bottom part of the throat that connects to the esophagus.

Treatment of Head and Neck cancer is often complex, reflecting the varied anatomy and pathology of the disease. It generally requires a multidisciplinary approach involving specialist surgeons and oncologists. Radical treatment may include combined surgery, chemotherapy, and radiotherapy. The treatment is individualised for the specific type, site, and stage of disease, and must take into account the patients fitness and wishes.